hf-report20121214

EPA 601/R-12/011 | December 2012 | www.epa.gov/hfstudy 

Study of the Potential Impacts of 

Hydraulic Fracturing on 

Drinking Water Resources 

PROGRESS REPORT 

United States Environmental Protection Agency 

Office of Research and Development

this page intentially left blank

Study of the Potential Impacts of 

Hydraulic Fracturing on 


PROGRESS REPORT 

US Environmental Protection Agency 

Office of Research and Development 

Washington, DC 

December 2012 

EPA/601/R-12/011

Study of the Potential Impacts of Hydraulic Fracturing 

on Drinking Water Resources: Progress Report December 2012 

Disclaimer 

Mention of trade names or commercial products does not constitute 

endorsement or recommendation for use. 

ii



Table of Contents 

Executive Summary .................................................................................................................................... 1 

1. Introduction ......................................................................................................................................... 5 

1.1. Stakeholder Engagement ...................................................................................................... 6 

2. Overview of the Research Program .................................................................................................. 8 

2.1. Research Questions ............................................................................................................ 12 

2.2. Environmental Justice ......................................................................................................... 21 

2.3. Changes to the Research Program..................................................................................... 22 

2.4. Research Approach ............................................................................................................ 23 

3. Analysis of Existing Data ................................................................................................................. 25 

3.1. Literature Review ................................................................................................................ 25 

3.2. Spills Database Analysis ..................................................................................................... 31 

3.3. Service Company Analysis ................................................................................................. 39 

3.4. Well File Review .................................................................................................................. 46 

3.5. FracFocus Analysis ............................................................................................................. 54 

4. Scenario Evaluations ........................................................................................................................ 62 

4.1. Subsurface Migration Modeling ........................................................................................... 62 

4.2. Surface Water Modeling ...................................................................................................... 75 

4.3. Water Availability Modeling ................................................................................................. 80 

5. Laboratory Studies ........................................................................................................................... 94 

5.1. Source Apportionment Studies ........................................................................................... 94 

5.2. Wastewater Treatability Studies ........................................................................................ 101 

5.3. Brominated Disinfection Byproduct Precursor Studies ..................................................... 107 

5.4. Analytical Method Development ........................................................................................ 112 

6. Toxicity Assessment ...................................................................................................................... 122 

7. Case Studies .................................................................................................................................... 127 

7.1. Introduction to Case Studies ............................................................................................. 127 

7.2. Las Animas and Huerfano Counties, Colorado ................................................................. 131 

7.3. Dunn County, North Dakota .............................................................................................. 137 

7.4. Bradford County, Pennsylvania ......................................................................................... 142 

7.5. Washington County, Pennsylvania ................................................................................... 148 

7.6. Wise County, Texas .......................................................................................................... 153 

8. Conducting High-Quality Science ................................................................................................. 159 

8.1. Quality Assurance ............................................................................................................. 159 

8.2. Peer Review ...................................................................................................................... 161 

9. Research Progress Summary and Next Steps ............................................................................. 163 

9.1. Summary of Progress by Research Activity ...................................................................... 163 

9.2. Summary of Progress by Water Cycle Stage ................................................................... 165 

iii



Table of Contents 

9.3. Report of Results............................................................................................................... 170 

9.4. Conclusions ....................................................................................................................... 170 

10. References ....................................................................................................................................... 172 

Appendix A: Chemicals Identified in Hydraulic Fracturing Fluids and Wastewater ........................ 196 

Appendix B: Stakeholder Engagement ................................................................................................. 246 

Appendix C: Summary of QAPPs .......................................................................................................... 251 

Appendix D: Divisions of Geologic Time .............................................................................................. 253 

Glossary ................................................................................................................................................... 254 

iv



List of Tables 

Table 1. Titles and descriptions of the research projects conducted as part of the EPA’s Study of the 

Potential Impacts of Hydraulic Fracturing on Drinking Water Resources ................................................... 10 

Table 2. Secondary research questions and applicable research projects identified for the water 

acquisition stage of the hydraulic fracturing water cycle ............................................................................. 15 

Table 3. Secondary research questions and applicable research projects identified for the chemical 

mixing stage of the hydraulic fracturing water cycle ................................................................................... 16 

Table 4. Secondary research questions and applicable research projects identified for the well injection 

stage of the hydraulic fracturing water cycle. .............................................................................................. 17 

Table 5. Secondary research questions and applicable research projects identified for the flowback and 

produced water stage of the hydraulic fracturing water cycle ..................................................................... 19 

Table 6. Secondary research questions and applicable research projects identified for the wastewater 

treatment and waste disposal stage of the hydraulic fracturing water cycle ............................................... 21 

Table 7. Research questions addressed by assessing the demographics of locations where hydraulic 

fracturing activities are underway ............................................................................................................... 21 

Table 8. Research activities and objectives ............................................................................................... 24 

Table 9. Classifications of information sources with examples .................................................................. 26 

Table 10. Description of factors used to assess the quality of existing data and information compiled 

during the literature review .......................................................................................................................... 27 

Table 11. Chemicals identified by the US House of Representatives Committee on Energy and 

Commerce as known or suspected carcinogens, regulated under the Safe Drinking Water Act (SDWA) or 

classified as hazardous air pollutants (HAP) under the Clean Air Act ........................................................ 29 

Table 12. Chemical appearing most often in hydraulic fracturing in over 2,500 products reported by 14 

hydraulic fracturing service companies as being used between 2005 and 2009 ....................................... 29 

Table 13. Secondary research questions addressed by reviewing existing databases that contain data 

relating to surface spills of hydraulic fracturing fluids and wastewater ....................................................... 31 

Table 14. Oil and gas-related spill databases used to compile information on hydraulic fracturing-related 

incidents ...................................................................................................................................................... 32 

Table 15. Data fields available in the NRC Freedom of Information Act database .................................... 34 

Table 16. Preset search terms available for the spill material, spill cause, and spill source data fields in 

the New Mexico Oil Conservation Division Spills Database ....................................................................... 36 

Table 17. Total number of incidents retrieved from the Pennsylvania Department of Environmental 

Protection's Compliance Reporting Database by varying inputs in the “Marcellus only” and inspections 

with “violations only data fields.” ................................................................................................................. 37 

Table 18. Secondary research questions addressed by analyzing data received from nine hydraulic 

fracturing service companies ...................................................................................................................... 39 

Table 19. Annual revenue and approximate number of employees for the nine service companies 

selected to receive the EPA’s September 2010 information request ......................................................... 40 

Table 20. Formulations, products, and chemicals reported as used or distributed by the nine service 

companies between September 2005 and September 2010 ...................................................................... 45 

Table 21. Secondary research questions addressed by the well file review research project ................... 46 

Table 22. The potential relationship between the topic areas in the information request and the stages of 

the hydraulic fracturing water cycle ............................................................................................................. 50 

v



List of Tables 

Table 23. Number of wells for which data were provided by each operator .............................................. 51 

Table 24. Secondary research questions addressed by extracting data from FracFocus, a nationwide 

hydraulic fracturing chemical registry .......................................................................................................... 54 

Table 25. Number of wells, by state, with data in FracFocus as of February 2012 ................................... 60 

Table 26. Secondary research questions addressed by simulating the subsurface migration of gases and 

fluids resulting from six possible mechanisms ............................................................................................ 62 

Table 27. Modules combined with the Transport of Unsaturated Groundwater and Heat (TOUGH)......... 71 

Table 28. Secondary research question addressed by modeling surface water discharges from 

wastewater treatment facilities accepting hydraulic fracturing wastewater ................................................ 75 

Table 29. Research questions addressed by modeling water withdrawals and availability in selected river 

basins .......................................................................................................................................................... 80 

Table 30. Water withdrawals for use in the Susquehanna River Basin ..................................................... 83 

Table 31. Well completions for select counties in Colorado within the Upper Colorado River Basin 

watershed .................................................................................................................................................... 86 

Table 32. Water withdrawals for use in the Upper Colorado River Basin .................................................. 86 

Table 33. Estimated total annual water demand for oil and gas wells in Colorado that were hydraulically 

fractured in 2010 and 2011 ......................................................................................................................... 88 

Table 34. Data and assumptions for future watershed availability and use scenarios modeled for the 

Susquehanna River Basin........................................................................................................................... 91 

Table 35. Data and assumptions for future watershed availability and use scenarios modeled for the 

Upper Colorado River Basin ....................................................................................................................... 91 

Table 36. Secondary research questions addressed by the source apportionment research project ....... 94 

Table 37. Historical average of monthly mean river flow and range of monthly means from 2006 

through 2011 for two rivers in Pennsylvania where the EPA collects samples for source apportionment 

research ...................................................................................................................................................... 96 

Table 38. Distance between sampling sites and wastewater treatment facilities on two rivers where the 

EPA collects samples for source apportionment research ......................................................................... 96 

Table 39. Inorganic analyses and respective instrumentation planned for source apportionment 

research ...................................................................................................................................................... 97 

Table 40. Median concentrations of selected chemicals and conductivity of effluent treated and 

discharged from two wastewater treatment facilities that accept oil and gas wastewater .......................... 99 

Table 41. Secondary research questions addressed by the wastewater treatability laboratory 

studies ....................................................................................................................................................... 101 

Table 42. Chemicals identified for initial studies on the adequacy of treatment of hydraulic fracturing 

wastewaters by conventional publicly owned treatment works, commercial treatment systems, and water 

reuse systems ........................................................................................................................................... 106 

Table 43. Secondary research questions potentially answered by studying brominated DBP formation 

from treated hydraulic fracturing wastewater ............................................................................................ 107 

Table 44. Disinfection byproducts regulated by the National Primary Drinking Water Regulations. ........ 109 

Table 45. Chemicals identified for analytical method testing activities .................................................... 114 

Table 46. Existing standard methods for analysis of selected hydraulic fracturing-related chemicals listed 

in Table 45................................................................................................................................................. 117 

vi



List of Tables 

Table 47. Secondary research questions addressed by compiling existing information on hydraulic 

fracturing-related chemicals ...................................................................................................................... 122 

Table 48. References used to develop a consolidated list of chemicals reportedly used in hydraulic 

fracturing fluids and/or found in flowback and produced water................................................................. 123 

Table 49. Secondary research questions addressed by conducting case studies................................... 127 

Table 50. General approach for conducting retrospective case studies .................................................. 129 

Table 51. Analyte groupings and examples of chemicals measured in water samples collected at the 

retrospective case study locations ............................................................................................................ 130 

Table 52. Background water quality data for the Killdeer Aquifer in North Dakota .................................. 139 

Table 53. Background (pre-drill) water quality data for ground water wells in Bradford County, 

Pennsylvania ............................................................................................................................................. 144 

Table 54. Background water quality data for all of Wise County, Texas, and its northern and southern 

regions ....................................................................................................................................................... 155 

Table A-1. List of CASRNs and names of chemicals reportedly used in hydraulic fracturing fluids ........ 197 

Table A-2. List of generic names of chemicals reportedly used in hydraulic fracturing fluids .................. 229 

Table A-3. List of CASRNs and names of chemicals detected in hydraulic fracturing wastewater ......... 240 

Table A-4. List of chemicals and properties detected in hydraulic fracturing wastewater ....................... 244 

Table C-1. QAPPs associated with the research projects discussed in this progress report. ................. 251 

vii



List of Figures 

Figure 1. Illustration of the five stages of the hydraulic fracturing water cycle ............................................. 8 

Figure 2. Potential drinking water issues associated with each stage of the hydraulic fracturing water 

cycle .............................................................................................................................................................. 9 

Figure 3. Illustration of the structure of the EPA’s Study of the Potential Impacts of Hydraulic Fracturing 

on Drinking Water Resources ..................................................................................................................... 12 

Figure 4. Fundamental research questions posed for each stage of the hydraulic fracturing water 

cycle ............................................................................................................................................................ 13 

Figure 5. Water acquisition......................................................................................................................... 14 

Figure 6. Chemical mixing .......................................................................................................................... 15 

Figure 7. Well injection ............................................................................................................................... 17 

Figure 8. Flowback and produced water .................................................................................................... 18 

Figure 9. Wastewater treatment and waste disposal ................................................................................. 20 

Figure 10. Locations of oil and gas production wells hydraulically fractured between September 2009 

and October 2010 ....................................................................................................................................... 44 

Figure 11. Locations of oil and gas production wells hydraulically fractured from September 2009 

through October 2010 ................................................................................................................................. 49 

Figure 12. Locations of 333 wells selected for the well file review............................................................. 52 

Figure 13. Example of data disclosed through FracFocus ......................................................................... 57 

Figure 14. Scenario A of the subsurface migration modeling project ........................................................ 64 

Figure 15. Scenario B1 of the subsurface migration modeling project ...................................................... 65 

Figure 16. Scenario B2 of the subsurface migration modeling project ...................................................... 66 

Figure 17. Scenario C of the subsurface migration modeling project ........................................................ 67 

Figure 18. Scenario D1 of the subsurface migration modeling project ...................................................... 68 

Figure 19. Scenario D2 of the subsurface migration modeling project ...................................................... 69 

Figure 20. The Susquehanna River Basin, overlying a portion of the Marcellus Shale, is one of two study 

areas chosen for water availability modeling .............................................................................................. 81 

Figure 21. The Upper Colorado River Basin, overlying a portion of the Piceance Basin, is one of two river 

basins chosen for water availability modeling ............................................................................................. 82 

Figure 22. Public water systems in the Susquehanna River Basin............................................................ 84 

Figure 23. Public water systems in the Upper Colorado River Basin ........................................................ 87 

Figure 24. Hydraulic fracturing wastewater flow in unconventional oil and gas extraction ...................... 102 

Figure 25. Generalized flow diagram for conventional publicly owned works treatment processes ........ 103 

Figure 26. Flow diagram of the EPA’s process leading to the development of modified or new analytical 

methods..................................................................................................................................................... 116 

Figure 27. Locations of the five retrospective case studies chosen for inclusion in the EPA’s Study of the 

Potential Impacts of Hydraulic Fracturing on Drinking Water Resources ................................................. 128 

Figure 28. Extent of the Raton Basin in southeastern Colorado and northeastern New Mexico ............. 132 

Figure 29. Locations of sampling sites in Las Animas and Huerfano Counties, Colorado ...................... 135 

Figure 30. Extent of the Bakken Shale in North Dakota and Montana .................................................... 137 

viii



List of Figures 

Figure 31. Location of sampling sites in Dunn County, North Dakota ..................................................... 140 

Figure 32. Extent of the Marcellus Shale, which underlies large portions of New York, Ohio, 

Pennsylvania, and West Virginia .............................................................................................................. 142 

Figure 33. Location of sampling sites in Bradford and Susquehanna Counties, Pennsylvania ............... 146 

Figure 34. Extent of the Marcellus Shale, which underlies large portions of New York, Ohio, 

Pennsylvania, and West Virginia .............................................................................................................. 148 

Figure 35. Sampling locations in Washington County, Pennsylvania ...................................................... 151 

Figure 36. Extent of the Barnett Shale in north-central Texas ................................................................. 153 

Figure 37. Location of sampling sites in Wise County, Texas ................................................................. 157 

Figure 38a. Summary of research projects underway for the first three stages of the hydraulic fracturing 

water cycle ................................................................................................................................................ 166 

Figure 38b. Summary of research projects underway for the first three stages of the hydraulic fracturing 

water cycle ................................................................................................................................................ 167 

Figure 39a. Summary of research projects underway for the last two stages of the hydraulic fracturing 

water cycle ................................................................................................................................................ 168 

Figure 39b. Summary of research projects underway for the last two stages of the hydraulic fracturing 

water cycle ................................................................................................................................................ 169 

Figure B-1. Timeline for technical roundtables and workshops ............................................................... 250 

Figure D-1. Divisions of geologic time approved by the USGS Geologic Names Committee (2010) ...... 253 

ix



ADQ 

API 

ASTM 

Br-DBP 

BTEX 

CASRN 

CBI 

CBM 

COGCC 

CWT 

DBP 

DSSTox 

FORTRAN 

GIS 

GWPC 

HAA 

HSPF 

IRIS 

LBNL 

LOAEL 

MCL 

MGD 

MSDS 

NAS 

NDIC 

NEMS 

NOM 

NPDES 

NRC 

NYSDEC 

PADEP 

POTW 

PPRTV 

PWS 

QA 

List of Acronyms and Abbreviations 

Audit of data quality 

American Petroleum Institute 

American Society for Testing and Materials 

Brominated disinfection byproduct 

Benzene, toluene, ethylbenzene, and xylene 

Chemical Abstracts Service Registration Number 

Confidential business information 

Coalbed methane 

Colorado Oil and Gas Conservation Commission 

Centralized waste treatment facility 

Disinfection byproduct 

Distributed Structure-Searchable Toxicity Database Network 

Formula translation 

Geographic information system 

Ground Water Protection Council 

Haloacetic acid 

Hydrologic Simulation Program FORTRAN 

Integrated Risk Information System 

Lawrence Berkeley National Laboratory 

Lowest observed adverse effect levels 

Maximum contaminant level 

Million gallons per day 

Material Safety Data Sheet 

National Academy of Sciences 

North Dakota Industrial Commission 

National Energy Modeling System 

Naturally occurring organic matter 

National Pollutant Discharge Elimination System 

National Response Center 

New York State Department of Environmental Conservation 

Pennsylvania Department of Environmental Protection 

Publicly owned treatment work 

Provisional Peer-Reviewed Toxicity Value 

Public water systems 

Quality assurance 

x



QAPP 

QC 

RRC 

SDWA 

SOP 

SRB 

SRBC 

SWAT 

TDS 

THM 

TOPKAT 

TOUGH 

TSA 

TSCA 

UCRB 

UIC 

US EIA 

US EPA 

US FWS 

US GAO 

US OMB 

USCB 

USDA 

USGS 

USHR 

WWTF 

List of Acronyms and Abbreviations 

Quality assurance project plan 

Quality control 

Railroad Commission of Texas 

Safe Drinking Water Act 

Standard operating procedure 

Susquehanna River Basin 

Susquehanna River Basin Commission 

Soil and Water Assessment Tool 

Total dissolved solids 

Trihalomethane 

Toxicity Prediction by Komputer Assisted Technology 

Transport of Unsaturated Groundwater and Heat 

Technical systems audit 

Toxic Substances Control Act 

Upper Colorado River Basin 

Underground injection control 

US Energy Information Administration 

US Environmental Protection Agency 

US Fish and Wildlife Service 

US Government Accountability Office 

US Office of Management and Budget 

US Census Bureau 

US Department of Agriculture 

US Geological Survey 

US House of Representatives 

Wastewater treatment facility 

xi



Executive Summary 

Natural gas plays a key role in our nation’s clean energy future. The United States has vast reserves 

of natural gas that are commercially viable as a result of advances in horizontal drilling and 

hydraulic fracturing technologies, which enable greater access to gas in rock formations deep 

underground. These advances have spurred a significant increase in the production of both natural 

gas and oil across the country. 

Responsible development of America’s oil and gas resources offers important economic, energy 

security, and environmental benefits. However, as the use of hydraulic fracturing has increased, so 

have concerns about its potential human health and environmental impacts, especially for drinking 

water. In response to public concern, the US House of Representatives requested that the US 

Environmental Protection Agency (EPA) conduct scientific research to examine the relationship 

between hydraulic fracturing and drinking water resources (USHR, 2009). 

In 2011, the EPA began research under its Plan to Study the Potential Impacts of Hydraulic 

Fracturing on Drinking Water Resources. The purpose of the study is to assess the potential impacts 

of hydraulic fracturing on drinking water resources, if any, and to identify the driving factors that 

may affect the severity and frequency of such impacts. Scientists are focusing primarily on 

hydraulic fracturing of shale formations to extract natural gas, with some study of other oil- and 

gas-producing formations, including tight sands, and coalbeds. The EPA has designed the scope of 

the research around five stages of the hydraulic fracturing water cycle. Each stage of the cycle is 

associated with a primary research question: 

• Water acquisition: What are the possible impacts of large volume water withdrawals from 

ground and surface waters on drinking water resources 

• Chemical mixing: What are the possible impacts of hydraulic fracturing fluid surface spills 

on or near well pads on drinking water resources 

• Well injection: What are the possible impacts of the injection and fracturing process on 

drinking water resources 

• Flowback and produced water: What are the possible impacts of flowback and produced 

water (collectively referred to as “hydraulic fracturing wastewater”) surface spills on or 

near well pads on drinking water resources 

• Wastewater treatment and waste disposal: What are the possible impacts of inadequate 

treatment of hydraulic fracturing wastewater on drinking water resources 

This report describes 18 research projects underway to answer these research questions and 

presents the progress made as of September 2012 for each of the projects. Information presented 

as part of this report cannot be used to draw conclusions about potential impacts to drinking water 

resources from hydraulic fracturing. The research projects are organized according to five different 

types of research activities: analysis of existing data, scenario evaluations, laboratory studies, 

toxicity assessments, and case studies. 

1



Analysis of Existing Data 

Data from multiple sources have been obtained for review and analysis. Many of the data come 

directly from the oil and gas industry and states with high levels of oil and gas activity. Information 

on the chemicals and practices used in hydraulic fracturing has been collected from nine companies 

that hydraulically fractured a total of 24,925 wells between September 2009 and October 2010. 

Additional data on chemicals and water use for hydraulic fracturing are being pulled from over 

12,000 well-specific chemical disclosures in FracFocus, a national hydraulic fracturing chemical 

registry operated by the Ground Water Protection Council and the Interstate Oil and Gas Compact 

Commission. Well construction and hydraulic fracturing records provided by well operators are 

being reviewed for 333 oil and gas wells across the United States; data within these records are 

being scrutinized to assess the effectiveness of current well construction practices at containing 

gases and liquids before, during, and after hydraulic fracturing. 

Data on causes and volumes of spills of hydraulic fracturing fluids and wastewater are being 

collected and reviewed from state spill databases in Colorado, New Mexico, and Pennsylvania. 

Similar information is being collected from the National Response Center national database of oil 

and chemical spills. 

In addition, the EPA is reviewing scientific literature relevant to the research questions posed in 

this study. A Federal Register notice was published on November 9, 2012, requesting relevant, peerreviewed 

data and published reports, including information on advances in industry practices and 

technologies. This body of literature will be synthesized with results from the other research 

projects to create a report of results. 

Scenario Evaluations 

Computer models are being used to identify conditions that may lead to impacts on drinking water 

resources from hydraulic fracturing. The EPA has identified hypothetical, but realistic, scenarios 

pertaining to the water acquisition, well injection, and wastewater treatment and waste disposal 

stages of the water cycle. Potential impacts to drinking water sources from withdrawing large 

volumes of water in semi-arid and humid river basins—the Upper Colorado River Basin in the west 

and the Susquehanna River Basin in the east—are being compared and assessed. 

Additionally, complex computer models are being used to explore the possibility of subsurface gas 

and fluid migration from deep shale formations to overlying aquifers in six different scenarios. 

These scenarios include poor well construction and hydraulic communication via fractures (natural 

and created) and nearby existing wells. As a first step, the subsurface migration simulations will 

examine realistic scenarios to assess the conditions necessary for hydraulic communication rather 

than the probability of migration occurring. 

In a separate research project, concentrations of bromide and radium at public water supply 

intakes located downstream from wastewater treatment facilities discharging treated hydraulic 

fracturing wastewater are being estimated using surface water transport models. 

2



Laboratory Studies 

Laboratory studies are largely focused on identifying potential impacts of inadequately treating 

hydraulic fracturing wastewater and discharging it to rivers. Experiments are being designed to test 

how well common wastewater treatment processes remove selected contaminants from hydraulic 

fracturing wastewater, including radium and other metals. Other experiments are assessing 

whether or not hydraulic fracturing wastewater may contribute to the formation of disinfection 

byproducts during common drinking water treatment processes, with particular focus on the 

formation of brominated disinfection byproducts, which have significant health concerns at high 

exposure levels. 

Samples of raw hydraulic fracturing wastewater, treated wastewater, and water from rivers 

receiving treated hydraulic fracturing wastewater have been collected for source apportionment 

studies. Results from laboratory analyses of these samples are being used to develop a method for 

determining if treated hydraulic fracturing wastewater is contributing to high chloride and bromide 

levels at downstream public water supplies. 

Finally, existing analytical methods for selected chemicals are being tested, modified, and verified 

for use in this study and by others, as needed. Methods are being modified in cases where standard 

methods do not exist for the low-level detection of chemicals of interest or for use in the complex 

matrices associated with hydraulic fracturing wastewater. Analytical methods are currently being 

tested and modified for several classes of chemicals, including glycols, acrylamides, ethoxylated 

alcohols, disinfection byproducts, radionuclides, and inorganic chemicals. 

Toxicity Assessments 

The EPA has identified chemicals reportedly used in hydraulic fracturing fluids from 2005 to 2011 

and chemicals found in flowback and produced water. Appendix A contains tables with over 1,000 

of these chemicals identified. Chemical, physical, and toxicological properties are being compiled 

for chemicals with known chemical structures. Existing models are being used to estimate 

properties in cases where information is lacking. At this time, the EPA has not made any judgment 

about the extent of exposure to these chemicals when used in hydraulic fracturing fluids or found in 

hydraulic fracturing wastewater, or their potential impacts on drinking water resources. 

Case Studies 

Two rounds of sampling at five case study locations in Colorado, North Dakota, Pennsylvania, and 

Texas have been completed. In total, water samples have been collected from over 70 domestic 

water wells, 15 monitoring wells, and 13 surface water sources, among others. This research will 

help to identify the source of any contamination that may have occurred. 

The EPA continues to work with industry partners to begin research activities at potential 

prospective case study locations, which involve sites where the research will begin before well 

construction. This will allow the EPA to collect baseline water quality data in the area. Water quality 

will be monitored for any changes throughout drilling, injection of fracturing fluids, flowback, and 

production. Samples of flowback and produced water will be used for other parts of the study, such 

as assessing the efficacy of wastewater treatment processes at removing contaminants in hydraulic 

fracturing wastewater. 

3



Invigorating the Research Study Through Consultation and Peer Review 

The EPA is committed to conducting a study that uses the best available science, independent 

sources of information, and a transparent, peer-reviewed process that will ensure the validity and 

accuracy of the results. The agency is working in consultation with other federal agencies, state and 

interstate regulatory agencies, industry, non-governmental organizations, and others in the private 

and public sector. In addition to workshops held in 2011, stakeholders and technical experts are 

being engaged through technical roundtables and workshops, with the first set of roundtables held 

November 14–16, 2012. These activities will provide the EPA with ongoing access to a broad range 

of expertise and data, timely and constructive technical feedback, and updates on changes in 

industry practices and technologies relevant to the study. Technical roundtables and workshops 

will be followed by webinars for the general public and posting of summaries on the study’s 

website. Increased stakeholder engagement will also allow the EPA to educate and inform the 

public of the study’s goals, design, and progress. 

To ensure scientifically defensible results, each research project is subjected to quality assurance 

and peer review activities. Specific quality assurance activities performed by the EPA make sure 

that the agency’s environmental data are of sufficient quantity and quality to support the data’s 

intended use. Research products, such as papers or reports, will be subjected to both internal and 

external peer review before publication, which make certain that the data are used appropriately. 

Published results from the research projects will be synthesized in a report of results that will 

inform the research questions associated with each stage of the hydraulic fracturing water cycle. 

The EPA has designated the report of results as a “Highly Influential Scientific Assessment,” which 

will undergo peer review by the EPA’s Science Advisory Board, an independent and external federal 

advisory committee that conducts peer reviews of significant EPA research products and activities. 

The EPA will seek input from individual members of an ad hoc expert panel convened under the 

auspices of the EPA Science Advisory Board. The EPA will consider feedback from the individual 

experts in the development of the report of results. 

Ultimately, the results of this study are expected to inform the public and provide decision-makers 

at all levels with high-quality scientific knowledge that can be used in decision-making processes. 

Looking Forward: From This Report to the Next 

Progress 

Report 

Science 

Advisory 

Board 

Individual 

Reports 

and Papers 

Draft 

Report of 

Results 

Science 

Advisory 

Board Peer 

Review 

Final 

Report of 

Results 

Technical Roundtables and Workshops, 

Public Webinars 

4



1. Introduction 

Oil and natural gas provided more energy in the United States for residential and industrial use 

than any other energy source in 2010—37% and 25%, respectively (US EIA, 2011a). Advances in 

technology and new applications of existing techniques, as well as supportive domestic energy 

policy and economic developments, have recently spurred an increase in oil and gas production 

across a wide range of geographic regions and geologic formations in the United States. Hydraulic 

fracturing is a technique used to produce economically viable quantities of oil and natural gas, 

especially from unconventional reservoirs, such as shale, tight sands, coalbeds, and other 

formations. Hydraulic fracturing involves the injection of fluids under pressures great enough to 

fracture the oil- and gas-producing formations. The resulting fractures are held open using 

“proppants,” such as fine grains of sand or ceramic beads, to allow oil and gas to flow from small 

pores within the rock to the production well. 

As the use of hydraulic fracturing has increased, so have concerns about its potential impact on 

human health and the environment, especially with regard to possible impacts on drinking water 

resources. 1 These concerns have increased as oil and gas exploration and development has spread 

from areas with a long history of conventional production to new areas with unconventional 

reservoirs, such as the Marcellus Shale, which extends from New York through parts of 

Pennsylvania, West Virginia, eastern Ohio, and western Maryland. 

In response to public concerns and anticipated growth in the oil and gas industries, the US Congress 

urged the US Environmental Protection Agency (EPA) to examine the relationship between 

hydraulic fracturing and drinking water resources (USHR, 2009): 

The conferees urge the agency to carry out a study on the relationship between hydraulic 

fracturing and drinking water, using a credible approach that relies on the best available 

science, as well as independent sources of information. The conferees expect the study to be 

conducted through a transparent, peer-reviewed process that will ensure the validity and 

accuracy of the data. The Agency shall consult with other federal agencies as well as 

appropriate state and interstate regulatory agencies in carrying out the study, which should 

be prepared in accordance with the agency’s quality assurance principles. 

In 2010, the EPA launched the planning of the current study and included multiple opportunities 

for the public and the Science Advisory Board 2 to provide input during the study planning process. 3 

The EPA’s Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources 

1 

Common concerns raised by stakeholders include potential impacts to air quality and ecosystems as well as sociologic 

effects (e.g., community changes). A more comprehensive list of concerns reported to the EPA during initial stakeholder 

meetings can be found in Appendix C of the EPA’s Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking 

Water Resources (EPA/600/R-11/121). 

2 

The Science Advisory Board is an independent and external federal advisory committee that conducts peer reviews of 

scientific matters for the EPA. 

3 

During summer 2010, the EPA engaged stakeholders in a dialogue about the study through facilitated meetings. 

Summaries of these meetings are available at http://www.epa.gov/hfstudy/publicoutreach.html. 

5



(subsequently referred to as the “Study Plan”) was finalized in November 2011 (US EPA, 2011e). 

The purpose of the EPA’s current study is to assess the potential impacts of hydraulic fracturing on 

drinking water resources, 4 if any, and to identify the driving factors that may affect the severity and 

frequency of such impacts. This study includes research on hydraulic fracturing to extract oil and 

gas from shale, tight sand, and coalbeds, focusing primarily on hydraulic fracturing of shale for gas 

extraction. It is intended to assess the potential impacts to drinking water resources from hydraulic 

fracturing as it is currently practiced and has been practiced in the past, and it is not intended to 

evaluate best management practices or new technologies. Emphasis is placed on identifying 

possible exposure pathways and hazards, providing results that can then be used to assess the 

potential risks to drinking water resources from hydraulic fracturing. Ultimately, results from the 

study are intended to inform the public and provide policymakers at all levels with high-quality 

scientific knowledge that can be used in decision-making. 

The body of this progress report presents the research progress made by the EPA, as of September 

2012, regarding the potential impacts of hydraulic fracturing on drinking water resources; 

information presented as part of this report cannot be used to draw conclusions about the 

proposed research questions. Chapters 3 through 7 provide project-specific updates that include 

background information on the research project, a description of the research methods, an update 

on the current status and next steps of the work, as well as a summary of the quality assurance (QA) 

activities to date; 5 these chapters are written for scientific and engineering professionals. All 

projects described in this progress report are currently underway, and nearly all are expected to be 

completed in the next few years. Results from individual projects will undergo peer review prior to 

publication. The EPA intends to synthesize the published results from these research projects in a 

report of results, described in more detail in Section 9.3. 

1.1. Stakeholder Engagement 

The EPA is committed to conducting this study in an open and transparent manner. During the 

development of the study, the EPA met with stakeholders from the general public; federal, state, 

regional and local agencies; tribes; industry; academia; and non-governmental organizations. 

Webinars and meetings with these separate groups were held to discuss the study scope, data gaps, 

opportunities for sharing data and conducting joint studies, current policies and practices for 

protecting drinking water resources, and the public engagement process. 

In addition to webinars and meetings, the EPA held a series of technical workshops in early 2011 on 

four subjects integral to hydraulic fracturing and the study: chemical and analytical methods, well 

construction and operation, chemical fate and transport, and water resource management. 6 

Technical experts from the oil and natural gas industry, academia, consulting firms, commercial 

laboratories, state and federal agencies, and environmental organizations were chosen to 

4 For this study, “drinking water resources” are considered to be any body of water, ground or surface, that could (now or 

in the future) serve as a source of drinking water for public or private water supplies. 

5 QA activities include implementation of quality assurance project plans (QAPPs), technical systems audits (TSAs), and 

audits of data quality (ADQs). These activities are described further in Section 8.1. 

6 Proceedings from the four technical workshops are available at http://www.epa.gov/hfstudy/technicalworkshops.html. 

6



participate in each of the workshops. The workshops gave EPA scientists the opportunity to 

interact with technical experts regarding current hydraulic fracturing technology and practices and 

to identify and design research related to the potential impacts of hydraulic fracturing on drinking 

water resources. Information presented during the workshops is being used to inform ongoing 

research. 

The EPA has recently announced additional opportunities for stakeholder engagement. The goals of 

this enhanced engagement process are to improve public understanding of the study, ensure that 

the EPA is current on changes in industry practices and technologies so that the report of results 

reflects an up-to-date picture of hydraulic fracturing operations, and obtain timely and constructive 

feedback on ongoing research projects. 

Stakeholders and technical experts are being engaged through the following activities: 

• Technical roundtables with invited experts from diverse stakeholder groups to discuss the 

work underway to answer key research questions and identify possible topics for 

technical workshops. The roundtables also give the EPA access to a broad and balanced 

range of expertise as well as data from outside the agency. 

• Technical workshops with experts invited to participate in more in-depth discussions and 

share expertise on discrete technical topics relevant to the study. 

• Information requests through a Federal Register notice, requesting that the public submit 

relevant studies and data—particularly peer-reviewed studies—for the EPA’s 

consideration, including information on advances in industry practices and technologies. 

• Study updates to a wide range of stakeholders, including the general public, states, tribes, 

academia, non-governmental organizations, industry, professional organizations, and 

others. 

• Periodic briefings with the EPA’s Science Advisory Board to provide updates on the 

progress of the study. 

These efforts will help: 

• Inform the EPA’s interpretation of the research being conducted as part of this study. 

• Identify additional data and studies that may inform the report or results. 

• Identify future research needs. 

Additional information on the ongoing stakeholder engagement process can be found in Appendix B 

and online at http://www.epa.gov/hfstudy/. The website includes the presentations made by the 

EPA during the technical roundtables held in November 2012 as well as a list of roundtable 

participants. Readers are encouraged to check this website for up-to-date information on upcoming 

webinars for the general public and proceedings from technical workshops, which are currently 

scheduled for spring 2013. 

7



2. Overview of the Research Program 

The EPA’s Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources is 

organized into five topics according to the potential for interaction between hydraulic fracturing 

and drinking water resources. These five topics—stages of the hydraulic fracturing water cycle— 

are illustrated in Figure 1 and include (1) water acquisition, (2) chemical mixing, (3) well injection, 

(4) flowback and produced water, and (5) wastewater treatment and waste disposal. 

Figure 1. Illustration of the five stages of the hydraulic fracturing water cycle. The cycle includes the acquisition of 

water needed for the hydraulic fracturing fluid, onsite mixing of chemicals with the water to create the hydraulic 

fracturing fluid, injection of the fluid under high pressures to fracture the oil- or gas-containing formation, recovery of 

flowback and produced water (hydraulic fracturing wastewater) after the injection is complete, and treatment and/or 

disposal of the wastewater. 

Figure 2 lists potential drinking water issues identified for each stage of the hydraulic fracturing 

water cycle. 

8



Water Use in Hydraulic 

Fracturing Operations 

Potential Drinking Water Issues 

Water Acquisition 

• Water availability 

• Impact of water withdrawal on water quality 

Chemical Mixing 

• Release to surface and ground water 

(e.g., onsite spills and/or leaks) 

• Chemical transportation accidents 

Well Injection 

• Accidental release to ground or surface water (e.g., well malfunction) 

• Fracturing fluid migration into drinking water aquifers 

• Formation fluid displacement into aquifers 

• Mobilization of subsurface formation materials into aquifers 

Flowback and 

Produced Water 

• Release to surface and ground water 

• Leakage from onsite storage into drinking water resources 

• Improper pit construction, maintenance, and/or closure 

Wastewater Treatment 

and Waste Disposal 

• Surface and/or subsurface discharge into surface and ground water 

• Incomplete treatment of wastewater and solid residuals 

• Wastewater transportation accidents 

Figure 2. Potential drinking water issues associated with each stage of the hydraulic fracturing water cycle. The potential issues help to define the fundamental 

research questions. Figure reprinted from the Study Plan (US EPA, 2011e). 

9



As described in the Study Plan, the potential issues led to the development of primary research 

questions that are supported by secondary research questions. The secondary research questions 

are addressed by the research projects listed in Table 1. Table 1 also provides short titles and 

descriptions of the research projects; these titles are used throughout the rest of the report. 

Table 1. Titles and descriptions of the research projects conducted as part of the EPA’s Study of the Potential 

Impacts of Hydraulic Fracturing on Drinking Water Resources. These titles are used throughout the rest of the report. 

Detailed descriptions of each project can be found in Chapters 3 through 7. 

Research Project 

Literature Review 

Spills Database Analysis 

Service Company Analysis 

Well File Review 

FracFocus Analysis 

Subsurface Migration Modeling 

Surface Water Modeling 

Water Availability Modeling 

Source Apportionment Studies 

Wastewater Treatability 

Studies 

Br-DBP Precursor Studies 

Analytical Method 

Development 

Description 


Review and assessment of existing papers and reports, focusing on 

peer-reviewed literature 

Analysis of selected federal and state databases for information on 

spills of hydraulic fracturing fluids and wastewaters 

Analysis of information provided by nine hydraulic fracturing service 

companies in response to a September 2010 information request on 

hydraulic fracturing operations 

Analysis of information provided by nine oil and gas operators in 

response to an August 2011 information request for 350 well files 

Analysis of data compiled from FracFocus, the national hydraulic 

fracturing chemical registry operated by the Ground Water Protection 

Council and the Interstate Oil and Gas Compact Commission 


Numerical modeling of subsurface fluid migration scenarios that 

explore the potential for gases and fluids to move from the fractured 

zone to drinking water aquifers 

Modeling of concentrations of selected chemicals at public water 

supplies downstream from wastewater treatment facilities that 

discharge treated hydraulic fracturing wastewater to surface waters 

Assessment and modeling of current and future scenarios exploring 

the impact of water usage for hydraulic fracturing on drinking water 

availability in the Upper Colorado River Basin and the Susquehanna 

River Basin 


Identification and quantification of the source(s) of high bromide and 

chloride concentrations at public water supply intakes downstream 

from wastewater treatment plants discharging treated hydraulic 

fracturing wastewater to surface waters 

Assessment of the efficacy of common wastewater treatment 

processes on removing selected chemicals found in hydraulic 

fracturing wastewater 

Assessment of the ability of bromide and brominated compounds 

present in hydraulic fracturing wastewater to form brominated 

disinfection byproducts (Br-DBPs) during drinking water treatment 

processes 

Development of analytical methods for selected chemicals found in 

hydraulic fracturing fluids or wastewater 

Table continued on next page 

10



Table continued from previous page 


Toxicity Assessment 

Retrospective Studies 

Las Animas and Huerfano 

Counties, Colorado 

Dunn County, North 

Dakota 

Bradford County, 

Pennsylvania 

Washington County, 

Pennsylvania 

Wise County, Texas 

Prospective Studies 

Description 


Toxicity assessment of chemicals reportedly used in hydraulic 

fracturing fluids or found in hydraulic fracturing wastewater 

Case Studies 

Investigations of whether reported drinking water impacts may be 

associated with or caused by hydraulic fracturing activities 

Investigation of potential drinking water impacts from coalbed 

methane extraction in the Raton Basin 

Investigation of potential drinking water impacts from a well blowout 

during hydraulic fracturing for oil in the Bakken Shale 

Investigation of potential drinking water impacts from shale gas 

development in the Marcellus Shale 


development in the Marcellus Shale 


development in the Barnett Shale 

Investigation of potential impacts of hydraulic fracturing through 

collection of samples from a site before, during, and after well pad 

construction and hydraulic fracturing 

Each project has been designed to inform answers to one or more of the secondary research 

questions with multiple projects informing answers to each secondary research question. The 

answers to the secondary research questions will then inform answers to the primary research 

questions. Figure 3 illustrates the relationship between water cycle stage, primary and secondary 

research questions, and research projects. 

11



Figure 3. Illustration of the structure of the EPA’s Study of the Potential Impacts of Hydraulic Fracturing on Drinking 

Water Resources. Results from multiple research projects may be used to inform answers to one secondary research 

question. Additionally, one research project may provide information to help answer multiple secondary research 

questions. Each research project falls under one type of research activity. 

2.1. Research Questions 

This section describes the activities that occur during each stage of the water cycle, potential 

drinking water issues, and primary research questions, which are listed in Figure 4. 7 It also 

introduces the secondary research questions and lists the associated research projects. This section 

is intended to offer a broad overview of the EPA’s study and direct the reader to further 

information in subsequent chapters of this progress report. Later chapters (Chapters 3 through 7) 

contain detailed information about the progress of individual research projects listed in Tables 2 

through 6 below. 

7 Additional information on the hydraulic fracturing water cycle stages and research questions can be found in the Study 

Plan. 

12



Water Use in Hydraulic 

Fracturing Operations 

Fundamental Research Question 

Water Acquisition 

What are the possible impacts of large volume water withdrawals 

from ground and surface waters on drinking water resources 

Chemical Mixing 

What are the possible impacts of surface spills on or near well pads 

of hydraulic fracturing fluids on drinking water resources 

Well Injection 

What are the possible impacts of the injection and fracturing 

process on drinking water resources 

Flowback and 

Produced Water 

What are the possible impacts of surface spills on or near well pads 

of flowback and produced water on drinking water resources 



What are the possible impacts of inadequate treatment of 

hydraulic fracturing wastewaters on drinking water resources 

Figure 4. Fundamental research questions posed for each stage of the hydraulic fracturing water cycle. Figure reprinted from the Study Plan (US EPA, 2011e). 

13



2.1.1. Water Acquisition: What are the possible impacts of large volume water 

withdrawals from ground and surface waters on drinking water resources 

Hydraulic fracturing fluids are usually water-based, with approximately 90% of the injected fluid 

composed of water (GWPC and ALL Consulting, 2009). Estimates of water needs per well have been 

reported to range from 65,000 gallons for coalbed methane (CBM) production up to 13 million 

gallons for shale gas production, depending on the characteristics of the formation being fractured 

and the design of the production well and fracturing operation (GWPC and ALL Consulting, 2009; 

Nicot et al., 2011). Five million gallons of water are equivalent to the water used by approximately 

50,000 people for one day. 8 The source of the water may vary, but is typically ground water, surface 

water, or treated wastewater, as illustrated in Figure 5. Industry trends suggest a recent shift to 

using treated and recycled produced water (or other treated wastewaters) as base fluids in 

hydraulic fracturing operations. 

Figure 5. Water acquisition. Water for hydraulic fracturing can be drawn from a variety of sources including surface 

water, ground water, treated wastewater generated during previous hydraulic fracturing operations, and other types of 

wastewater. 

The EPA is working to better characterize the amounts and sources of water currently being used 

for hydraulic fracturing operations, including recycled water, and how these withdrawals may 

impact local drinking water quality and availability. To that end, secondary research questions have 

been developed, as well as the research projects listed in Table 2. 

8 This assumes that the average American uses approximately 100 gallons of water per day. See http://www.epa.gov/ 

watersense/pubs/indoor.html. 

14



Table 2. Secondary research questions and applicable research projects identified for the water acquisition stage of 

the hydraulic fracturing water cycle. The table also identifies the sections of this report that contain detailed 

information about the listed research projects. 

Secondary Research Questions Applicable Research Projects Section 

Literature Review 3.1 

How much water is used in hydraulic fracturing 

operations, and what are the sources of this water 

How might water withdrawals affect short- and longterm 

water availability in an area with hydraulic 

fracturing activity 

What are the possible impacts of water withdrawals 

for hydraulic fracturing operations on local water 

quality 

Service Company Analysis 3.3 

Well File Review 3.4 

FracFocus Analysis 3.5 

Water Availability Modeling 4.3 


Water Availability Modeling 4.3 


2.1.2. Chemical Mixing: What are the possible impacts of surface spills on or near well 

pads of hydraulic fracturing fluids on drinking water resources 

Once onsite, water is mixed with chemicals to create the hydraulic fracturing fluid that is pumped 

down the well, as illustrated in Figure 6. The fluid serves two purposes: to create pressure to 

propagate fractures and to carry the proppant into the fracture. Chemicals are added to the fluid to 

change its properties (e.g., viscosity, pH) in order to optimize the performance of the fluid. Roughly 

1% of water-based hydraulic fracturing fluids are composed of various chemicals, which is 

equivalent to 50,000 gallons for a shale gas well that uses 5 million gallons of fluid. 

Figure 6. Chemical mixing. Water is mixed with chemicals and proppant onsite to create the hydraulic fracturing fluid 

immediately before injection. 

15



Hydraulic fracturing operations require large quantities of supplies, equipment, water, and vehicles. 

Onsite storage, mixing, and pumping of hydraulic fracturing fluids may result in accidental releases, 

such as spills or leaks. 9 Released fluids could then flow into nearby surface water bodies or 

infiltrate into the soil and near-surface ground water, potentially reaching drinking water 

resources. In order to explore the potential impacts of surface releases of hydraulic fracturing fluids 

on drinking water resources, the EPA is: (1) compiling information on reported spills; (2) 

identifying chemical additives used in hydraulic fracturing fluids and their chemical, physical, and 

toxicological properties; and (3) gathering data on the environmental fate and transport of selected 

hydraulic fracturing chemical additives. These activities correspond to the secondary research 

questions and research projects described in Table 3. 

Table 3. Secondary research questions and applicable research projects identified for the chemical mixing stage of 

the hydraulic fracturing water cycle. The table also identifies the sections of this report that contain detailed 

information about the listed research projects. 


What is currently known about the frequency, severity, 

and causes of spills of hydraulic fracturing fluids and 

additives 

What are the identities and volumes of chemicals 

used in hydraulic fracturing fluids, and how might this 

composition vary at a given site and across the 

country 

What are the chemical, physical, and toxicological 

properties of hydraulic fracturing chemical additives 

If spills occur, how might hydraulic fracturing chemical 

additives contaminate drinking water resources 


Spills Database Analysis 3.2 






Analytical Method Development 5.4 

Toxicity Assessment 6 


Retrospective Case Studies 7 

2.1.3. Well Injection: What are the possible impacts of the injection and fracturing 

process on drinking water resources 

The hydraulic fracturing fluid is pumped down the well at pressures great enough to fracture the 

oil- or gas-containing rock formation, as shown in Figure 7 for both horizontal and vertical well 

completions. Production wells are drilled and completed in order to best and most efficiently drain 

the geological reservoir of its hydrocarbon resources. This means that wells may be drilled and 

completed vertically (panel b in Figure 7), vertically at the top and then horizontally at the bottom 

(panel a), or in other configurations deviating from vertical, known as “deviated wells.” 

9 As noted in the Study Plan, transportation-related spills of hydraulic fracturing chemical additives and wastewater are 

outside of the scope of the current study. 

16



(a) 

(b) 

Figure 7. Well injection. During injection, hydraulic fracturing fluids are pumped into the well at high pressures, which 

are sustained until the fractures are formed. Hydraulic fracturing can be used with both (a) deep, horizontal well 

completions and (b) shallower, vertical well completions. Horizontal wells are typically used in formations such as 

tight sandstones, carbonate rock, and shales. Vertical wells are typically used in formations for conventional 

production and coalbed methane. 

Within this stage of the hydraulic fracturing water cycle, the EPA is studying a number of scenarios 

that may lead to changes in local drinking water resources, including well construction failure and 

induced fractures intersecting existing natural (e.g., faults or fractures) or man-made (e.g., 

abandoned wells) features that may act as conduits for contaminant transport. Table 4 lists the 

secondary research questions and research projects that address these concerns. 

Table 4. Secondary research questions and applicable research projects identified for the well injection stage of the 

hydraulic fracturing water cycle. The table also identifies the sections of this report that contain detailed information 

about the listed research projects. 



How effective are current well construction practices Service Company Analysis 3.3 

at containing gases and fluids before, during, and Well File Review 3.4 

after fracturing 

Subsurface Migration Modeling 4.1 



Can subsurface migration of fluids or gases to 

drinking water resources occur, and what local 

geologic or man-made features might allow this 



Subsurface Migration Modeling 4.1 


17



2.1.4. Flowback and Produced Water: What are the possible impacts of surface spills on 

or near well pads of flowback and produced water on drinking water resources 

When the injection pressure is reduced, the direction of fluid flow reverses, leading to the recovery 

of flowback and produced water. For this study, “flowback” is the fluid returned to the surface after 

hydraulic fracturing has occurred, but before the well is placed into production, while “produced 

water” is the fluid returned to the surface after the well has been placed into production. 10 They are 

collectively referred to as “hydraulic fracturing wastewater” and may contain chemicals injected as 

part of the hydraulic fracturing fluid, substances naturally occurring in the oil- or gas-producing 

formation, 11 hydrocarbons, and potential reaction and degradation products. 

Figure 8. Flowback and produced water. During this stage, the pressure on the hydraulic fracturing fluid is reduced 

and the flow is reversed. The flowback and produced water contain hydraulic fracturing fluids, native formation water, 

and a variety of naturally occurring substances picked up by the wastewater during the fracturing process. The fluids 

are separated from any gas or oil produced with the water and stored in either tanks or an open pit. 

As depicted in Figure 8, the wastewater is typically stored onsite in impoundment pits or tanks. 

Onsite transfer and storage of hydraulic fracturing wastewater may result in accidental releases, 

such as spills or leaks, which may reach nearby drinking water resources. The potential impacts to 

drinking water resources from flowback and produced water are similar to the potential impacts 

identified in the chemical mixing stage of the hydraulic fracturing water cycle, with the exception of 

different fluid compositions for injected fluids and wastewater. Therefore, the secondary research 

10 Produced water is a product of all oil and gas wells, including wells that have not been hydraulically fractured. 

11 Substances naturally found in hydraulically fractured formations may include brines, trace elements (e.g., mercury, 

lead, arsenic), naturally occurring radioactive material (e.g., radium, thorium, uranium), gases (e.g., natural gas, hydrogen 

sulfide), and organic material (e.g., organic acids, polycyclic aromatic hydrocarbons, volatile organic compounds). 

18



questions and associated research projects are similar. The secondary research questions and 

applicable research projects are listed in Table 5. 

Table 5. Secondary research questions and applicable research projects identified for the flowback and produced 

water stage of the hydraulic fracturing water cycle. The table also identifies the sections of this report that contain 

detailed information about the listed research projects. 



What is currently known about the frequency, severity, Spills Database Analysis 3.2 

and causes of spills of flowback and produced water Service Company Analysis 3.3 


What is the composition of hydraulic fracturing 

wastewaters, and what factors might influence this 

composition 

What are the chemical, physical, and toxicological 

properties of hydraulic fracturing wastewater 

constituents 

If spills occur, how might hydraulic fracturing 

wastewater contaminate drinking water resources 




Analytical Method Development 5.4 

Toxicity Assessment 6 



2.1.5. Wastewater Treatment and Waste Disposal: What are the possible impacts of 

inadequate treatment of hydraulic fracturing wastewaters on drinking water 

resources 

Estimates of the fraction of hydraulic fracturing wastewater recovered vary by geologic formation 

and range from 10% to 70% of the injected hydraulic fracturing fluid (GWPC and ALL Consulting, 

2009; US EPA, 2011f). For a hydraulic fracturing job that uses 5 million gallons of hydraulic 

fracturing fluid, this means that between 500,000 and 3.5 million gallons of fluid will be returned to 

the surface. As illustrated in Figure 9, the wastewater is generally managed through disposal into 

deep underground injection control (UIC) wells, 12 treatment followed by discharge to surface water 

bodies, 13 or treatment followed by reuse. 

12 Underground injection of fluids related to oil and gas production (including flowback and produced water) is 

authorized by the Safe Drinking Water Act. 

13 Treatment processes involving discharge to surface waters are authorized by the Clean Water Act and the National 

Pollutant Discharge Elimination System program. 

19



Figure 9. Wastewater treatment and waste disposal. Flowback and produced water is frequently disposed of in deep 

injection wells, but may also be trucked, or in some cases piped, to a disposal or recycling facility. Once treated, the 

wastewater may be reused in subsequent hydraulic fracturing operations or discharged to surface water. 

Understanding the treatment, disposal, and reuse of flowback and produced water from hydraulic 

fracturing activities is important. For example, contaminants present in these waters may be 

inadequately treated at publicly owned treatment works (POTWs), discharges from which may 

threaten downstream drinking water intakes, as depicted in Figure 9. 14 Table 6 summarizes the 

secondary research questions and the applicable research projects for each question. 

14 As noted in the Study Plan, this study does not propose to evaluate the potential impacts of underground injection or 

the associated potential impacts due to transport and storage leading up to ultimate disposal in a UIC well. 

20



Table 6. Secondary research questions and applicable research projects identified for the wastewater treatment and 

waste disposal stage of the hydraulic fracturing water cycle. The table also identifies the sections of this report that 

contain detailed information about the listed research projects. 


What are the common treatment and disposal Literature Review 3.1 

methods for hydraulic fracturing wastewater, and Well File Review 3.4 

where are these methods practiced 


How effective are conventional POTWs and 


commercial treatment systems in removing organic 

and inorganic contaminants of concern in hydraulic Wastewater Treatability Studies 5.2 



What are the potential impacts from surface water 

Surface Water Modeling 4.2 

disposal of treated hydraulic fracturing wastewater on 

drinking water treatment facilities 

Source Apportionment Studies 5.1 

Br-DBP Precursor Studies 5.3 

2.2. Environmental Justice 

Environmental justice is the fair treatment and meaningful involvement of all people regardless of 

race, color, national origin, or income, with respect to the development, implementation, and 

enforcement of environmental laws, regulations, and policies. 15 

During the planning process, some stakeholders raised concerns about environmental justice and 

hydraulic fracturing, while others stated that hydraulic fracturing–related activities provide 

benefits to local communities. In its review of the draft Study Plan, the EPA’s Science Advisory 

Board supported the inclusion in the study of an environmental justice analysis as it pertains to the 

potential impacts on drinking water resources. The EPA, therefore, attempted to conduct a 

screening to provide insight into the research questions in Table 7. 

Table 7. Research questions addressed by assessing the demographics of locations where hydraulic fracturing 

activities are underway. 

Fundamental Research Question 

Does hydraulic fracturing 

disproportionately occur in or near 

communities with environmental 

justice concerns 

Secondary Research Questions 

• Are large volumes of water being disproportionately 

withdrawn from drinking water resources that serve 

communities with environmental justice concerns 

• Are hydraulically fractured oil and gas wells 

disproportionately located near communities with 

environmental justice concerns 

• Is wastewater from hydraulic fracturing operations being 

disproportionately treated or disposed of (via POTWs or 

commercial treatment systems) in or near communities with 

environmental justice concerns 

15 The EPA’s definition of environmental justice can be found at 

http://www.epa.gov/environmentaljustice/basics/index.html and was informed by E.O. 12898. 

21



Environmental justice screening uses easily obtained environmental and demographic information 

to highlight locations where additional review (i.e., information collection or analysis) may be 

warranted (US EPA, 2012c). Screenings do not examine whether co-location of specific activities 

and communities with certain demographics (e.g., low-income, non-white minority, young children, 

and elderly subpopulations) may lead to any positive or negative impacts on a given community. 

Nationwide data on the locations of water withdrawals and wastewater treatment associated with 

hydraulic fracturing activities are difficult to obtain. The EPA was not able to identify 

comprehensive data sources that identify the locations of water withdrawals associated with 

hydraulic fracturing or facilities receiving hydraulic fracturing wastewaters. Geographic data on 

hydraulic fracturing-only water use (rather than general oil and gas water use) are limited, and the 

available data are aggregated by regions too large for an environmental justice analysis. Data on 

commercial and publicly owned treatment works accepting hydraulic fracturing wastewater were 

found to be inconsistent between states or difficult to obtain. 

Data on the locations of hydraulically fractured oil and gas production wells considered for the 

environmental justice screen are available from two sources: data provided to the EPA from nine 

hydraulic fracturing service companies (see Section 3.3) and data obtained from FracFocus (Section 

3.5). The service company data set includes county-level locations of approximately 25,000 oil and 

gas wells hydraulically fractured between September 2009 and October 2010. In total, 590 of the 

3,221 counties in the United States contained wells hydraulically fractured by the nine service 

companies during the period under analysis. In comparison, the FracFocus data set includes 

latitude/longitude and county-level information on the location of roughly 11,000 wells 

hydraulically fractured between January 2009 and February 2012. In total, only 251 of the 3,221 

counties in the United States contained wells reported to FracFocus during this time period. 

The county-level resolution provided by the service company data set is insufficient for 

determining whether hydraulic fracturing activities are occurring in communities that possess 

characteristics associated with environmental justice populations. Finer resolution is needed since 

counties can contain a multitude of communities, townships, and even cities, with diverse 

populations. Data obtained from FracFocus provide well locations at finer resolution (i.e., specific 

latitude/longitude coordinates), which may provide further opportunity for either state- or 

nationwide environmental justice screens. 

2.3. Changes to the Research Program 

The EPA has significantly modified some of the research projects since the publication of the Study 

Plan. These modifications are discussed below. 

FracFocus Analysis. In early 2011, the Ground Water Protection Council and the Interstate Oil and 

Gas Compact Commission jointly launched a new national registry for chemicals used in hydraulic 

fracturing, called FracFocus. This registry is an online repository where oil and gas well operators 

can upload information regarding the chemical composition of hydraulic fracturing fluids used in 

specific oil and gas production wells. Extracting data from FracFocus allows the EPA to gather 

publicly available, nationwide data on the water volumes and chemicals used in hydraulic 

fracturing operations, as reported by oil and gas operating companies. These data are being 

22



analyzed to identify chemicals used in hydraulic fracturing fluids as well as the geographic 

distribution of water and chemical use. 

Prospective Case Studies. The EPA identified the location of one of the prospective case studies as De 

Soto Parish, Louisiana, in the Haynesville Shale. Due to scheduling conflicts, the location in De Soto 

Parish is no longer being considered for a prospective case study. 

The EPA continues to work with industry partners to identify locations and develop research 

activities for prospective case studies. As part of these case studies, the EPA intends to monitor 

local water quality for up to a year or more after hydraulic fracturing occurs. It is likely, therefore, 

that the prospective case studies will be completed after the report of results. In that event, results 

from any prospective case studies will be published in a follow-up report. 

Chemical Prioritization. As part of the toxicity assessment research project, the EPA is compiling 

chemical, physical, and toxicological properties for chemicals reportedly used in hydraulic 

fracturing fluids and/or detected in flowback and produced water. One aspect of the planned 

second phase of this work was to include prioritizing a subset of these chemicals for future toxicity 

screening using high throughput screening assays. However, consistent with recommendations of 

the Science Advisory Board, the agency will not conduct high throughput screening assays at this 

time on a subset of these chemicals, but will continue efforts to identify, evaluate, and prioritize 

existing toxicity data. 

Reactions Between Hydraulic Fracturing Fluids and Shale. Based on research already being 

conducted by the US Department of Energy and academic institutions on the interactions between 

hydraulic fracturing fluids and various rock formations, 16 the EPA has decided to discontinue its 

work in this area. The EPA continues to believe in the importance of research to address research 

questions associated with this project, but has decided to rely upon work being conducted by 

another federal agency. 

Therefore, the EPA has removed two research questions associated with this project: 

• How might hydraulic fracturing fluids change the fate and transport of substances in the 

subsurface through geochemical interactions 

• What are the chemical, physical, and toxicological properties of substances in the 

subsurface that may be released by hydraulic fracturing operations 

2.4. Research Approach 

The research projects listed in Table 1 and discussed in detail in Chapters 3 through 7 of this 

progress report require a broad range of scientific expertise in environmental and petroleum 

engineering, ground water hydrology, fate and transport modeling, and toxicology, as well as many 

other disciplines. Consequently, the EPA is using a transdisciplinary research approach that 

16 See, for example, research underway by the US Department of Energy’s National Energy Technology Laboratory 

(http://www.netl.doe.gov/publications/factsheets/rd/R%26D166.pdf) and Penn State 3S Laboratory 

(http://3s.ems.psu.edu/research.html). 

23



integrates various types of expertise from inside and outside the agency. The research projects fall 

into five categories: analysis of existing data, case studies, scenario modeling and evaluation, 

laboratory studies, and toxicology assessments. Table 8 summarizes the five main types of research 

activities occurring as part of this study and their objectives. Figure 3 illustrates the relationship 

between the research activities and the research projects and questions. 

Table 8. Research activities and objectives. Each research project falls under one type of research activity. 

Activity 

Analysis of existing data 

Scenario evaluations 

Laboratory studies 

Toxicity assessment 

Case studies 

Retrospective 

Prospective 

Objective 

Gather and summarize existing data from various sources to provide 

current information on hydraulic fracturing activities; includes information 

requested of hydraulic fracturing service companies and oil and gas 

operators* 

Use computer modeling to assess the potential for hydraulic fracturing to 

impact drinking water resources 

Conduct targeted experiments to test and develop analytical detection 

methods and to study the fate and transport of selected chemicals during 

wastewater treatment and discharge to surface water 

Identify chemicals used in hydraulic fracturing fluids or reported to be in 

hydraulic fracturing wastewater and compile available chemical, physical, 

and toxicological properties 

Study sites with reported contamination to understand the underlying 

causes and potential impacts to drinking water resources 

Develop understanding of hydraulic fracturing processes and their 

potential impacts on drinking water resources 

* For more information on the information requests, see http://www.epa.gov/hfstudy/analysis-of-existing-data.html. 

24



3. Analysis of Existing Data 

The objective of this approach is to gather and summarize data from many sources to provide 

current information on hydraulic fracturing activities. The EPA is collecting and analyzing data on 

chemical spills, surface water discharges, and chemicals found in hydraulic fracturing fluids and 

wastewater, among others. These data have been collected from a variety of sources, including state 

and federal agencies, industry, and public sources. Included among these sources is information 

received after the September 2010 letter requesting data from nine hydraulic fracturing service 

companies and the August 2011 letter requesting well files from nine oil and gas well operators. 17 

This chapter includes progress reports for the following projects: 

3.1. Literature Review.................................................................................................................................................. 25 

Review and assessment of existing papers and reports, focusing on peer-reviewed literature 

3.2. Spills Database Analysis...................................................................................................................................... 31 

Analysis of selected federal and state databases for information on spills of hydraulic 

fracturing fluids and wastewaters 

3.3. Service Company Analysis ................................................................................................................................. 39 

Analysis of information provided by nine hydraulic fracturing service companies in response to 

a September 2010 information request on hydraulic fracturing operations 

3.4. Well File Review..................................................................................................................................................... 46 

Analysis of information provided by nine oil and gas operators in response to an August 2011 

information request for 350 well files 

3.5. FracFocus Analysis................................................................................................................................................ 54 

Analysis of data compiled from FracFocus, the national hydraulic fracturing chemical registry 

operated by the Ground Water Protection Council and the Interstate Oil and Gas Compact 

Commission 

3.1. Literature Review 

3.1.1. Relationship to the Study 

The EPA is gathering and assessing literature relevant to all secondary research questions. 

3.1.2. Project Introduction 

An extensive review of existing literature is an important component of the EPA’s study of the 

relationship between hydraulic fracturing and drinking water resources. The objective of this 

literature review is to identify and analyze data and literature relevant to all secondary research 

questions. This objective will be met by reviewing a wide range of information sources on the five 

stages of the hydraulic fracturing water cycle. Sources identified through the literature review are 

subject to a quality review to support decisions regarding their inclusion in the EPA’s report of 

17 Copies of these information requests are available at http://www.epa.gov/hfstudy/analysis-of-existing-data.html. 

25



results. Information gathered during the literature review will be synthesized with results from the 

other research projects described in this progress report to answer the research questions posed in 

the Study Plan and summarized in Chapter 2. 

3.1.3. Research Approach 

Existing literature and data is being identified through a variety of methods, including conducting a 

search of published documents, searching online databases such as OnePetro 18 and Web of 

Knowledge SM 19 and reviewing materials provided to the EPA through technical workshops, 

comment submissions, and the Science Advisory Board’s review of the draft study plan. 20 Once 

identified, sources are classified as shown in Table 9. 

Table 9. Classifications of information sources with examples. Once identified, existing literature and data sources 

are classified according to the following categories. 

Source Classification Examples 

Journal publications, reports, and white papers developed by federal and 

Peer-reviewed literature 

state agencies 

Non-peer-reviewed 

literature 

Unpublished data 

Non-peer-reviewed government documents; congressional documents 

and hearing proceedings; workshop proceedings; Ph.D. theses; nonpeer-reviewed 

reports and white papers from industry, associations, and 

non-governmental organizations 

Online databases, personal communications, unpublished manuscripts, 

unpublished government data 

Once sources are grouped into the categories shown in Table 9 above, assessment factors are used 

to further evaluate their merit. Five assessment factors are being used to evaluate the quality of 

existing data and information: soundness, applicability and utility, clarity and completeness, 

uncertainty and variability, and evaluation and review (US EPA, 2003a). These factors are described 

in more detail in Table 10. 

18 OnePetro is an online library of technical literature for the oil and gas exploration and production industry. It can be 

accessed at http://www.onepetro.org/. 

19 Thomson Reuters Web of Knowledge SM is a research platform that provides access to objective content and powerful 

tools to search, track, measure, and collaborate in the sciences, social sciences, arts, and humanities. It can be accessed at 

http://wokinfo.com/. 

20 A list of literature recommended by the Science Advisory Board can be found on pages 29–34 of the Science Advisory 

Board’s review of the draft Study Plan, available at http://yosemite.epa.gov/sab/sabproduct.nsf/0/ 

2BC3CD632FCC0E99852578E2006DF890/$File/EPA-SAB-11-012-unsigned.pdf. 

26



Table 10. Description of factors used to assess the quality of existing data and information compiled during the 

literature review. The assessment factors are identified in (US EPA, 2003a). 

Factors 

Soundness 

Applicability and utility 

Clarity and 

completeness 

Uncertainty and 

variability 

Evaluation and review 

Description 

The extent to which the scientific and technical procedures, measures, 

methods, or models employed to generate the information are reasonable 

for, and consistent with, the intended application 

The extent to which the information is relevant for the agency’s intended use 

The degree of clarity and completeness with which the data, assumptions, 

methods, quality assurance, sponsoring organizations, and analyses 

employed to generate the information are documented 

The extent to which the variability and uncertainty (quantitative and 

qualitative) in the information or in the procedures, measures, methods or 

models are evaluated and characterized 

The extent of independent verification, validation, and peer review of the 

information or of the procedures, measures, methods, or models 

Information included in the report of results will be drawn primarily from peer-reviewed 

publications. Peer-reviewed publications contain the most reliable information, although some 

portions of the report may contain compilations of data from a variety of sources and source 

classifications. Non-peer-reviewed and unpublished sources will not form the sole basis of any 

conclusions presented in the report of results. Generally, these sources will be used to support 

results presented from peer-reviewed work, enhance understanding based on peer-reviewed 

sources, identify promising ideas of investigation, and discuss further in-depth work needed. 

The criteria in Table 10 are applied to all sources to ensure that the EPA is using high-quality data. 

In some cases, these data may not strictly meet the quality guidelines outlined in Table 10, though 

they still provide valuable information. Principal investigators on this project are responsible for 

deciding whether to include these data and providing all available background information in order 

to place these results in the appropriate context. 

3.1.4. Status and Preliminary Data 

The literature review is currently underway. Water acquisition, chemical mixing, and flowback and 

produced water are the only stages of the hydraulic fracturing water cycle for which specific 

updates are available at this time. 

Water Acquisition. The water acquisition literature review is intended to complement the analysis 

of existing data on hydraulic fracturing fluid source water resources from nine service companies 

(see Section 3.3) and nine oil and gas operators (Section 3.4), as well as the analysis of existing data 

from FracFocus (Section 3.5). Work at this stage is directed at answering three secondary research 

questions: 

• How much water is used in hydraulic fracturing operations, and what are the sources of 

this water 

• How might water withdrawals affect short- and long-term water availability in an area with 

hydraulic fracturing activity 

27



• What are the possible impacts of water withdrawals for hydraulic fracturing operations on 

local water quality 

To date, work has focused on the first question regarding the volumes and sources of water 

acquired for use in hydraulic fracturing. The literature review focuses on the major basins where 

hydraulic fracturing is prevalent in order to present a national perspective on water use. 

Hydrocarbon plays that will be highlighted include the Barnett, Eagle Ford, and Haynesville Shales 

in the South, the Bakken Shale in the Midwest, and the Marcellus and Utica Shales in the East. 

The Barnett, Eagle Ford, and Haynesville Shales have undergone the most thorough analysis as 

reflected by the availability of peer-reviewed literature pertaining to the Texas oil and gas basins 

and to the water resources in the southern United States. The Bakken Shale has also been 

investigated extensively, although very little peer-reviewed literature was available for analysis as 

of July 2012. Instead, information on volumes and sources of water in the Bakken Shale comes 

largely from news articles. Water acquisition in the Marcellus and Utica Shales has not yet been 

analyzed, but water withdrawal data is expected to be available. 

Chemical Mixing and Flowback and Produced Water. Existing scientific literature is being reviewed 

to identify how chemicals used in hydraulic fracturing fluids or present in hydraulic fracturing 

wastewaters may contaminate drinking water resources as a result of surface spills of these fluids. 

Relevant information from the literature review will help address the research questions listed 

below: 

• If spills occur, how might hydraulic fracturing chemical additives contaminate drinking 

water resources 

• If spills occur, how might hydraulic fracturing wastewaters contaminate drinking water 

resources 

The EPA has identified chemicals for further review based on publicly available information on 

hazard and frequency of use. Tables 11 and 12 identify a subset of chemicals used in hydraulic 

fracturing fluids as reported to the US House of Representatives’ Committee on Energy and 

Commerce by 14 hydraulic fracturing service companies as being used in hydraulic fracturing fluids 

between 2005 and 2009 (USHR, 2011). Table 11 lists chemicals that are known or suspected 

carcinogens, regulated by the Safe Drinking Water Act (SDWA), or listed as Clean Air Act hazardous 

air pollutants. The Committee included the hazardous air pollutant designation for listed chemicals 

because some may impact drinking water (e.g., methanol and ethylene glycol). Table 12 lists the 

chemical components appearing most often in over 2,500 hydraulic fracturing products used 

between 2005 and 2009, according to the information reported to the Committee. 

28



Table 11. Chemicals identified by the US House of Representatives Committee on Energy and Commerce as known 

or suspected carcinogens, regulated under the Safe Drinking Water Act (SDWA) or classified as hazardous air 

pollutants (HAP) under the Clean Air Act. The number of products containing each chemical is also listed. These 

chemicals were reported by 14 hydraulic fracturing service companies to be in a total of 652 different products used 

between 2005 and 2009. Reproduced from USHR (2011). 

Chemicals Category No. of Products 

Methanol HAP 342 

Ethylene glycol HAP 119 

Naphthalene Carcinogen, HAP 44 

Xylene SDWA, HAP 44 

Hydrochloric acid HAP 42 

Toluene SDWA, HAP 29 

Ethylbenzene SDWA, HAP 28 

Diethanolamine HAP 14 

Formaldehyde Carcinogen, HAP 12 

Thiourea Carcinogen 9 

Benzyl chloride Carcinogen, HAP 8 

Cumene HAP 6 

Nitrilotriacetic acid Carcinogen 6 

Dimethyl formamide HAP 5 

Phenol HAP 5 

Benzene Carcinogen, SDWA, HAP 3 

Di (2-ethylhexyl) phthalate Carcinogen, SDWA, HAP 3 

Acrylamide Carcinogen, SDWA, HAP 2 

Hydrofluoric acid HAP 2 

Phthalic anhydride HAP 2 

Acetaldehyde Carcinogen, HAP 1 

Acetophenone HAP 1 

Copper SDWA 1 

Ethylene oxide Carcinogen, HAP 1 

Lead Carcinogen, SDWA, HAP 1 

Propylene oxide Carcinogen, HAP 1 

p-Xylene HAP 1 

Table 12. Chemical appearing most often in hydraulic fracturing in over 2,500 products reported by 14 hydraulic 

fracturing service companies as being used between 2005 and 2009. Reproduced from USHR (2011). 

Chemical 

No. of Products 

Methanol 342 

Isopropanol 274 

Crystalline silica 207 

2-Butoxyethanol 126 

Ethylene glycol 119 

Hydrotreated light petroleum distillates 89 

Sodium hydroxide 80 

29



Existing scientific literature is also being reviewed for the chemicals identified as part of the 

analytical method development research project (see Table 45 in Section 5.4). This table includes 

chemicals associated with injected hydraulic fracturing fluids and wastewater. 

Literature searches have found papers describing impacts from spills of produced water (Healy et 

al., 2011; Healy et al., 2008), although the emphasis is often on ecosystem impacts rather than 

drinking water impacts. Produced water has the greatest number of literature publications for 

reported spills compared to hydraulic fracturing fluids and flowback, because produced water must 

be managed in both conventional and unconventional oil and gas production. Papers describing 

impacts from spills of produced water from conventional oil and gas production wells are being 

considered as part of the literature review because the chemical composition of flowback and 

produced water from hydraulically fractured formations is similar to that of conventional 

reservoirs (Hayes, 2009). Publications about impoundment leaks or other types of surface 

impoundment failures are also included within the scope of the flowback and produced water 

literature review. 

Because some of the chemicals commonly used in hydraulic fracturing fluid are ubiquitous, a very 

large numbers of papers have been found. To narrow the scope, recent review papers on 

environmental impacts and other published summaries on transport of chemicals or classes of 

chemicals are being sought. Information on the chemicals listed in Tables 11, 12, and 45 has been 

collected primarily by searching peer-reviewed literature using keyword searches of major 

databases, including Web of Knowledge SM , Proquest, 21 and OnePetro. Review papers describing 

impacts from spills of hydraulic fracturing fluids containing benzene, toluene, ethylbenzene, and 

xylenes (Farhadian et al., 2008; Seagren and Becker, 2002; Seo et al., 2009); ethylene glycol 

(Staples et al., 2001); phenol (Van Schie and Young L.Y., 2000); surfactants (Scott and Jones, 2000; 

Sharma et al., 2009; Soares A. et al., 2008; Van Ginkel, 1996); and napthalenes (Haritash and 

Kaushik, 2009; Rogers et al., 2002) have been identified. Other sources of information include the 

Government Accountability Office report on federal research on produced water (US GAO, 2012); 

toxicological profiles from the Agency for Toxic Substances and Disease Registry, which often 

contain brief summaries of information on transport and transformation; 22 EPA software systems 

(US EPA, 2012b); and chemical reference handbooks (Howard, 1989; Howard et al., 1991; 

Montgomery, 2000). Specific discussion of abiotic transformations is included in some of these 

references, including the Agency for Toxic Substances and Disease Registry Toxicological Profiles, 

environmental organic chemistry references (Schwarzenbach et al., 2002), and review papers 

(Stangroom et al., 2010). 

Chemical and physical properties of most of the organic chemicals listed in Tables 11 and 12 have 

been summarized, and the analysis is nearly complete. As more chemicals of interest are identified 

throughout the study, the number of chemicals may expand. Fewer publications exist for less 

21 ProQuest can be accessed at http://www.proquest.com. 

22 See, for example, pages 258–259 of ATSDR (2007). 

30



common chemicals, however, and obtaining enough data to characterize these chemicals’ potential 

to affect drinking water resources may not be feasible. 

3.1.5. Next Steps 

Next steps include completing the literature review for questions pertaining to sources, volumes, 

and impacts of large volume water withdrawals on local water quality and water availability. 

Further review of the water acquisition and quantity literature will specifically address the volumes 

and sources of water used in the Marcellus and Utica Shales. The literature review on chemical 

mixing and flowback and produced water for information that may answer the secondary research 

questions for those water stages will be completed. The EPA will also review relevant literature on 

all the remaining secondary research questions. 

3.1.6. Quality Assurance Summary 

The quality assurance project plan (QAPP) for the literature review, “Data and Literature 

Evaluation for the EPA’s Study of the Potential Impacts of Hydraulic Fracturing (HF) on Drinking 

Water Resources (Version 0),” was approved on September 4, 2012 (US EPA, 2012f). Links to the all 

of the QAPPs are provided in Appendix C. 

3.2. Spills Database Analysis 


The primary research questions for the chemical mixing and flowback and produced water stages 

of the hydraulic fracturing water cycle focus on the potential for hydraulic fracturing fluids and 

wastewaters to be spilled on the surface, possibly impacting nearby drinking water resources. This 

project searches various data sources in order to answer the research questions listed in Table 13. 

Table 13. Secondary research questions addressed by reviewing existing databases that contain data relating to 

surface spills of hydraulic fracturing fluids and wastewater. 

Water Cycle Stage 

Chemical mixing 

Flowback and produced water 

Applicable Research Questions 

What is currently known about the frequency, severity, and causes of 

spills of hydraulic fracturing fluids and additives 

What is currently known about the frequency, severity, and causes of 

spills of flowback and produced water 


Hydraulic fracturing operations require large quantities of chemical additives, equipment, water, 

and vehicles, which may create risks of accidental releases, such as spills or leaks. Surface spills or 

releases can occur as a result of events such as tank ruptures, equipment or surface impoundment 

failures, overfills, vandalism, accidents, ground fires, or improper operations. Released fluids might 

flow into nearby surface water bodies or infiltrate into the soil and near-surface ground water, 

potentially reaching drinking water aquifers (NYSDEC, 2011). 

Over the past few years, there have been numerous media reports of spills of hydraulic fracturing 

fluids and wastewater (US EPA, 2011e). While the media reports have highlighted specific surface 

spills of hydraulic fracturing fluids and wastewaters, the frequency and typical causes of these spills 

31



remain unclear. Additionally, these reports may tend to highlight severe spills and may not 

accurately reflect the distribution, number, and severity of spills across the country. The EPA is 

compiling information on surface spills of hydraulic fracturing fluids and wastewaters as reported 

in federal and state databases to assess the frequency, severity, and causes of spills associated with 

hydraulic fracturing. Hydraulic fracturing fluid and wastewater spill information was also collected 

from nine hydraulic fracturing service companies and nine oil and gas operators, as discussed in 

Sections 3.3 and 3.4, respectively. Together, these data are being used to describe spills of hydraulic 

fracturing fluids and wastewater and to identify factors that may lead to potential impacts on 

drinking water resources. 


There is currently no national repository or database that contains spill data focusing primarily on 

hydraulic fracturing operations. In the United States, spills relating to oil and gas operations are 

reported to the National Response Center (NRC) and various state regulatory entities. For example, 

in Colorado, spills are reported to the Oil and Gas Conservation Commission, within the Department 

of Natural Resources, while in Texas, oil and gas related spills are reported to the Texas Railroad 

Commission and the Texas Commission on Environmental Quality, depending on which agency has 

jurisdiction. The EPA has identified one federal database and databases in five states for review, as 

listed in Table 14. The NRC database was selected because it is the only nationwide source of 

information on releases of hazardous substances and oil. Spill databases from Colorado, New 

Mexico, Pennsylvania, Texas, and Wyoming were chosen for further consideration due to the large 

number of hydraulically fractured oil and gas wells found in those states. 23 

Table 14. Oil and gas-related spill databases used to compile information on hydraulic fracturing-related incidents. 

Source 

National Response Center Freedom of 

Information Act data 

Colorado Oil and Gas Information System 

New Mexico Energy, Minerals and Natural 

Resources Department 

Pennsylvania Department of 

Environmental Protection Compliance 

Reporting Database 

Texas Railroad Commission and Texas 

Commission on Environmental Quality 

Wyoming Department of Environmental 

Quality Water Quality Enforcement Actions 

Website 

http://www.nrc.uscg.mil/foia.html 

http://www.cogcc.state.co.us 

https://wwwapps.emnrd.state.nm.us/ocd/ocdpermitting/ 

Data/Incidents/Spills.aspx 

http://www.emnrd.state.nm.us/ocd/Statistics.html 

http://www.depreportingservices.state.pa.us/ 

ReportServer/Pages/ReportViewer.aspx/Oil_Gas/ 

OG_Compliance 

Consolidated Compliance and Enforcement Data System 

(not publicly available online) 

http://deq.state.wy.us/out/WQenforcementactions.htm 

Each of the publicly available databases identified in Table 14 has been searched for spill incidents 

related to hydraulic fracturing operations. The search timeframe is limited to incidents between 

January 1, 2006, and April 30, 2012, in order to encompass the increase in hydraulic fracturing 

23 Based on data provided by nine hydraulic fracturing service companies of oil and gas wells fractured between 2009 and 

2010. See Figure 10 in Section 3.3. 

32



activity seen during that period. To the extent that data are publicly available, electronically 

accessible, and readily searchable for spill-related data, the following information is being compiled 

about specific hydraulic fracturing-related spill incidents: 

• Data source 

• Location 

• Chemicals/products spilled 

• Estimated/reported volume of spill 

• Cause of spill 

• Reported impact to nearby water resources 

• Proximity of the spill to the well or well pad 

The information obtained from the NRC and state databases is being reviewed with information 

received in response to the EPA’s September 2010 information request to nine hydraulic fracturing 

service companies (see Section 3.3) and the EPA’s August 2011 information request to nine oil and 

gas operators (Section 3.4). The resulting list of unique spill incidents is being queried to identify 

common causes of hydraulic fracturing-related spills, chemicals spilled, the ranges of volumes 

spilled, and the potential impacts of these spills to drinking water sources. Because the main focus 

of this study is to identify hydraulic fracturing-related spills on the well pad that may impact 

drinking water resources, the following topics are not included in the scope of this project: 

• Transportation-related spills (except when tanker trucks act as mobile portable storage 

containers for chemicals, products, and hydraulic fracturing wastewater used on drilling 

sites) 

• Drilling mud spills 

• Air releases 

• Spills associated with disposal through underground injection control wells 

• Erosion and sediment control issues 

• Spill drills and exercise events (per NRC data) 

• Well construction and permitting violations 

• Leaks from pipes transporting flowback and produced water from one site to another for 

reuse 


The EPA has initiated work on all publicly available databases listed in Table 14. This section 

summarizes the type of information available in each database and lists the criteria being used to 

search each database. 

National Response Center Freedom of Information Act Data. This database contains nationwide data 

on releases of hazardous substances and oil that trigger the federal notification requirements under 

33



several laws. The NRC is the sole federal point of contact for reporting of all hazardous substances 

releases and oil spills. Its information comes from people who arrive on the scene or discover a 

spell, then call the NRC hotline or submit a Web-based report form. The information collected by 

the NRC during the initial notification call may include the suspected responsible party; the incident 

location by county, state, and nearest city; the released material and volume or quantity released; 

and a description of the incident, incident causes, affected media, initial known damages, and 

remedial actions taken. This information is often based on the estimates made by persons 

responding to a spill and may be incomplete. More accurate information may be available once a 

response is complete, but this database is not updated with such information. 

The data fields that can be used to query the NRC database are listed in Table 15. Many of these 

fields only allow searches from a fixed (i.e., drop-down) list, although several of the data fields are 

open to any input. None of the search terms in the fixed lists are specific to hydraulic fracturing or 

oil and gas exploration and production. 

Table 15. Data fields available in the NRC Freedom of Information Act database. ”Fixed list data fields” contain a 

fixed list of search terms form which the user can choose. “Open data fields” can receive any input from the user. 

Fixed List Data Fields 

Type of call 

Incident date range 

State 

County 

Incident type 

Incident cause 

Medium affected 

Open Data Fields 

NRC report number 

Nearest city 

Suspected responsible company 

Material name 

Given the query restrictions, broad searches are being conducted using the listed responsible 

company, material name, and incident date range fields (i.e., leaving other fields blank). 

The resulting spills are being examined to determine their relevance to this study. Since the 

database includes only initial incident reports, information is frequently missing or estimated, such 

as total volume spilled. Also, misspellings in the reports or the use of different vocabulary can cause 

the search engine to miss relevant incidents. 

Colorado. The Colorado Oil and Gas Conservation Commission gathers data regarding pits, 

spills/releases, and complaints relating to oil and gas exploration and production. Oil and gas 

operators are required to report spills and releases that occur as a result of oil and gas operations, 

in accordance with Colorado Oil and Gas Conservation Commission Rule 906 (COGCC, 2011). 

Reported information is entered into the Colorado Oil and Gas Information System 

Inspection/Incident Database. Each report documents the type of facility, volume spilled and/or 

recovered, ground water impacts, depth to shallowest ground water, surface water impacts, 

distance to nearest surface water, cause of spill, and a detailed description of the incident. The 

34



database is searchable by API number, 24 complainant, operator, facility/lease, location, remediation 

project number, and document number. Since there is no searchable data field in the database to 

indicate whether the spill is related to hydraulic fracturing, the database was queried for all 

spill/release reports. Only reports dated from January 1, 2006, to April 30, 2012, were selected for 

further review. This search returned over 2,500 reports that are currently being evaluated to 

identify incidents related to hydraulic fracturing activities. 

New Mexico. The Oil Conservation Division of the State of New Mexico Energy, Minerals and Natural 

Resources Department tracks information, in two separate databases, on both spill incidents and 

incidents where liquids in pits have contaminated ground water. Release Notification and 

Corrective Action forms are submitted to the Oil Conservation Divisions District offices. Spills can 

be reported by industry representatives or state agency personnel. 

The spills database is searchable by facility and well names, incident type, operator, location, lease 

type, spilled material, spill cause, spill source, and the spill referrer (person who reported the 

incident). The database was initially searched using the spill material, spill cause, and spill source 

data fields. Each of these fields can only be searched using the preset search terms listed in Table 

16. The initial search was conducted using the search terms in bold in Table 16. The EPA is 

currently examining the resulting list of spills to determine their relevancy to this study and is 

considering running additional queries to collect more information. 

24 The API (American Petroleum Institute) number is a unique, permanent, numeric identifier assigned to each well 

drilled for oil and gas in the United States. 

35



Table 16. Preset search terms available for the spill material, spill cause, and spill source data fields in the New 

Mexico Oil Conservation Division Spills Database. Terms in bold have been searched. 

Spill Material Spill Cause Spill Source 

All All All 

Acid Blowout Coupling 

Brine water Corrosion Gas compression station 

B.S. & W (basic sediment & water) Equipment failure Dump line 

Chemical (specify) Fire Motor 

Condensate Freeze Flowline—injection 

Diesel Human error Flowline—production 

Drilling mud/fluid Lightning Frac tank 

Glycol Other Fitting 

Gasoline Normal operations Injection header 

Gelled brine (frac fluid) Vandalism Other (specify) 

Hydrogen sulfate Vehicular accident Pit (specify) 

Crude oil 

Motor oil 

Natural gas (methane) 

Natural gas liquids 

Lube oil 

Other (specify) 

Produced water 

Unknown 

Pipeline (any) 

Production tank 

Pump 

Separator 

Transport 

Unknown 

Valve 

Well 

Water tank 

The database containing information regarding contamination of ground water due to pits tracks 

only the current company, facility name, tracking number, county, location, and status of the 

contamination incidents. Details regarding the contamination incident and the relation of the event 

to hydraulic fracturing are not included. Additional research is needed to determine if the pit 

information is related to hydraulic fracturing. 

Pennsylvania. The Pennsylvania Department of Environmental Protection’s Compliance Reporting 

Database provides information on oil and gas inspections, violations, enforcement actions, and 

penalties assessed and collected. Users can search the database according to the following fixedvariable 

data fields: county, municipality, date inspected, operator, Marcellus only, 25 inspections 

with violations only, and resolved violations only. 

Table 17 displays the total number of incidents retrieved for four different queries, all using a date 

range of January 1, 2006, to April 30, 2012. 

25 This data field was recently changed to “unconventional only” (last accessed July 6, 2012). 

36



Table 17. Total number of incidents retrieved from the Pennsylvania Department of Environmental Protection's 

Compliance Reporting Database by varying inputs in the “Marcellus only” and inspections with “violations only data 

fields.” In all cases, “no” was entered in the “resolved violations only” field. 

Marcellus Only 

Inspections with 

Violations Only 

Yes 

No 

Yes 

Yes 

No 

Yes 

No 

No 

* Error message received when formatting results of this query. 

Total Number of 

Incidents Retrieved 

25,687 

4,319 

18,700 

Unknown* 

The queries shown in Table 17 returned information collected during inspections that found 

violations and/or when spills are reported. An incident or inspection may have multiple violations, 

leading to a large total number of violations retrieved from the database. The EPA’s initial effort 

focused on the query that returned the fewest violations, which totaled 4,319 inspections with 

violations specific to the Marcellus Shale region. Inspection and violation comment fields for each 

incident are being reviewed to identify incidents related to hydraulic fracturing activities. 

Texas. Representatives of the Railroad Commission of Texas, the Texas Commission on 

Environmental Quality, and the Texas General Land Office have confirmed that there is no central 

database in Texas on hydraulic fracturing-related spills. In Texas, a memorandum of understanding 

between the Railroad Commission and Commission on Environmental Quality identifies the 

jurisdiction of these agencies over waste materials resulting from exploring, developing, producing, 

and refining oil and gas. Pursuant to this understanding, oil and gas operators are required to 

report spills to the Railroad Commission, which maintains a publicly available database of spills of 

petroleum, oil, and condensate. The EPA has reviewed this database and determined that it does 

not include chemical spills; most of the spills reported in the database are crude oil spills. 

Therefore, there will be no further analysis of this database. 

The Commission on Environmental Quality is Texas’ lead agency in responding to spills of all 

hazardous substances that may cause pollution or lower air quality pursuant to the Texas 

Hazardous Substances Spill Prevention and Control Act (Texas Water Code §26.261). The 

Commission on Environmental Quality may generate an investigation, inspection, or complaint 

report in response to emergency spill notifications. These reports are submitted to the state’s 

Consolidated Compliance and Enforcement Data System. However, the investigation and inspection 

reports in this database are not available electronically on the Texas Commission on Environmental 

Quality’s website or at their Central Files Room. 

Other attempts were made to obtain information on potential ground water contamination 

incidents related to hydraulic fracturing by examining the Joint Groundwater Monitoring and 

Contamination Reports prepared by the Texas Groundwater Protection Committee; this effort was 

unsuccessful in getting the relevant incident details. The abovementioned searches for hydraulic 

fracturing spill-related data may not be an exhaustive investigation of all available information 

from Texas’ state agencies or organizations, but other publicly available sources of information 

have not been located at this time. 

37



Wyoming. The Wyoming Department of Environmental Quality maintains a publicly available 

database of water quality enforcement actions. This database includes reports of water quality 

violations categorized by the year they occurred, from 2006 to 2012. None of the reports 

differentiate between hydraulic fracturing-related incidents and those due to other stages of oil and 

gas development. Many of the oil and gas-related violations were for CBM produced water 

discharges, such as to surface water. Due to the lack of information to differentiate between 

hydraulic fracturing-related incidents and other oil and gas-related incidents, there will be no 

further analysis of this dataset. 

The spills database analysis has several important limitations: 

• Potential underreporting. This affects the EPA’s ability to assess the number or frequency 

of hydraulic fracturing-related spill incidents, since it is likely that some spills are not 

reported to the NRC or state agencies. 

• Variation in reporting requirements for different sources. This makes it difficult to 

categorize reported spills as hydraulic fracturing-related and to comprehensively identify 

the causes, chemical identity, and volumes of hydraulic fracturing-related spills. 

• The lack of electronic accessibility of some state-reported data on oil and gas-related spills 

and emergency responses. This also significantly impacts the comprehensiveness of the 

available information. 


As noted, the EPA is reviewing the list of spill incidents generated by searching the NRC, Colorado, 

New Mexico, and Pennsylvania databases to identify incidents related to hydraulic fracturing 

activities. Spill incidents identified through this review will be combined with data received from 

nine hydraulic fracturing service companies (see Section 3.3) and nine oil and gas operators 

(Section 3.4) to create a master database of hydraulic fracturing-related spills from these sources. 

The compiled information will be examined to identify, where possible, common causes of 

hydraulic fracturing-related spills, chemicals spilled, and ranges of volumes spilled. Specific steps 

will then include: 

• Creating a reference table of information gathered from all incidences determined to be 

related to hydraulic fracturing. 

• Reviewing this reference table for trends in the causes and volumes of hydraulic 

fracturing-related spills. 


The QAPP for the analysis of publicly available information on surface spills related to hydraulic 

fracturing, “Hydraulic Fracturing (HF) Surface Spills Data Analysis (Version 1),” was approved on 

August 6, 2012 (US EPA, 2012l). The project underwent a technical systems audit (TSA) by the 

designated EPA QA Manager on August 27, 2012. The methods and products being developed under 

the project adhered to the approved QAPP, and no corrective actions were identified. 

38



3.3. Service Company Analysis 


The EPA asked nine hydraulic fracturing service companies for information about hydraulic 

fracturing operations conducted from 2005 to 2010. The data are being analyzed for information 

that can be used to inform answers to the research questions in Table 18. 

Table 18. Secondary research questions addressed by analyzing data received from nine hydraulic fracturing service 

companies. 


Water acquisition 


Well injection 

Flowback and 

produced water 


• How much water is used in hydraulic fracturing operations, and what are 

the sources of this water 

• What is currently known about the frequency, severity, and causes of 

spills of hydraulic fracturing fluids and additives 

• What are the identities and volumes of chemicals used in hydraulic 

fracturing fluids, and how might this composition vary at a given site and 

across the country 

• How effective are current well construction practices at containing gases 

and fluids before, during, and after fracturing 

• Can subsurface migration of fluids or gases to drinking water resources 

occur and what local geologic or man-made features may allow this 

• How might hydraulic fracturing fluids change the fate and transport of 

substances in the subsurface through geochemical interactions 

• What is currently known about the frequency, severity, and causes of 

spills of flowback and produced water 

• What is the composition of hydraulic fracturing wastewaters, and what 

factors might influence this composition 


Hydraulic fracturing is typically performed by a service company under a contract with the oil or 

gas production well operator. The service companies possess detailed information regarding the 

implementation of hydraulic fracturing, from design through fracturing. In September 2010, the 

EPA requested information from nine companies on the chemical composition of hydraulic 

fracturing fluids used from 2005 to 2010, standard operating procedures (SOPs), impacts of 

chemicals on human health and the environment, and the locations of oil and gas wells 

hydraulically fractured in 2009 and 2010. The EPA is analyzing the information received from the 

service companies to better understand current hydraulic fracturing operating practices and to 

answer the research questions listed above. 

Service Companies Selected. Nine service companies received the information request: BJ Services 

Company, Complete Production Services, Halliburton, Key Energy Services, Patterson-UTI Energy, 

RPC, Schlumberger, Superior Well Services, and Weatherford International. These companies 

reflect a range of industry market share and variation in company size. The EPA estimated that BJ 

Services Company, Halliburton, and Schlumberger performed approximately 95% of hydraulic 

fracturing services in the United States in 2003 (US EPA, 2004b), and the three companies reported 

39



the highest annual revenues for 2009 of the nine companies selected for the information request. 26 

The remaining six companies represent mid-sized and small companies performing hydraulic 

fracturing services between 2005 and 2009. 27 Table 19 shows the annual revenue, number of 

employees, and company services reported by the companies to the US Securities and Exchange 

Commission in the 2009 Form 10-K. 

Table 19. Annual revenue and approximate number of employees for the nine service companies selected to receive 

the EPA’s September 2010 information request. The companies reflect a range of industry market share and 

company sizes. Information was obtained from Form 10-K, filed with the US Securities and Exchange Commission in 

2009. 

Company 

Annual Revenue for 

2009 (Millions) 

Number of 

Employees 

(Approximate) 

BJ Services Company* $4,122 14,400 

Complete Production Services $1,056 5,200 

Halliburton $14,675 51,000 

Key Energy Services $1,079 8,100 

Patterson-UTI Energy $782 4,200 

RPC $588 2,000 

Schlumberger $22,702 77,000 

Superior Well Services $399 1,400 

Weatherford International $8,827 52,000 

* BJ Services reports on a fiscal year calendar ending on September 30. 

Three of the nine service companies that reported information to the EPA were acquired by other 

companies since 2010. Baker Hughes completed the purchase of BJ Services Company in April 2010, 

Patterson-UTI Energy purchased Key Energy Services in October 2010, and Superior Well Services 

acquired Complete Production Services in February 2012. 


The EPA received responses to the September 2010 information request from each of the nine 

service companies. Data and information relevant to the research questions posed above were 

collected and organized in Microsoft Excel spreadsheets and Microsoft Access databases. Each 

company reported information in various organizational formats and using different descriptive 

terms; therefore, the EPA has put all nine datasets into a consistent format for analysis and 

resolving any issues associated with terminology, data gaps, or inconsistencies. This selection of 

information serves as the basis for targeted queries and data summaries described below. The 

queries and data summaries have been designed to answer the secondary research questions listed 

in Table 18. 

Much of the data and information received by the EPA was claimed to be confidential business 

information (CBI) under the Toxic Substances Control Act (TSCA). Five of the nine companies, 

26 Information was obtained from the 2009 Form 10-K, filed with the US Securities and Exchange Commission. 

27 Annual revenue and number of employees were used as indicators of company size. 

40



however, also provided non-confidential information. 28 Because the majority of the information has 

been claimed as CBI, the analyses described below are being conducted in accordance with the 

procedures outlined in the EPA’s TSCA CBI Protection Manual (US EPA, 2003b). All results are 

treated as CBI until determinations are made or until masking has been done to prevent disclosure 

of CBI information. 

Summary of Service Company Operations. The EPA is using information provided by the companies 

to write a narrative description of the range of their operations, which includes information on the 

role of the service companies in each stage of the hydraulic fracturing water cycle. 

Information has been compiled on the number and location of wells hydraulically fractured by the 

nine service companies between September 2009 and October 2010, resulting in a map that 

displays the number of wells fractured per county as reported by the companies. This information 

is intended to illustrate the intensity and geographic distribution of hydraulic fracturing activities 

by these companies. 

Water Acquisition. The following information from the service company data on volumes, quality, 

and sources of water used in hydraulic fracturing fluids is being summarized and will include: 

• Water use by shale play. The range of water volumes used based on the shale play in which 

the well is located. (The companies did not provide information on geologic formations 

other than shale.) 

• Procedures and considerations relating to water acquisition. Summary of any SOPs, water 

quality requirements, water source preferences, and decision processes described in the 

submissions from the nine service companies. 

Chemical Mixing. The following information collected from the service companies is being 

assembled to identify the composition of different hydraulic fracturing fluid formulations and the 

factors that influence formulation composition: 

• Chemical name 

• Chemical formula 

• Chemical Abstracts Service Registration Number (CASRN) 

• Material Safety Data Sheets (MSDSs) for each fluid product 

• Concentration of each chemical in each fluid product 

• Manufacturer of each product and chemical 

• Purpose and use of each chemical in each fluid product 

28 The non-confidential information is available on the federal under docket number EPA-HQ-ORD-2010-0674 or via 

http://www.regulations.gov/#!searchResults;rpp=10;po=0;s=epa-hq-ord-2010-0674. 

41



For the purposes of the analysis, the EPA defines a “product” as an additive composed of a single 

chemical or several chemicals. A “chemical” is an individual chemical included in a product. A “fluid 

formulation” is the entire suite of products and carrier fluid injected into a well during hydraulic 

fracturing. The following information from the service company data on chemicals, products, and 

fluid formulations is being summarized: 

• Formulations, products, and product function. The formulations reported by the nine 

service companies and the number and types of products used in those formulations. 

• Products, chemicals in those products and concentrations, and manufacturer of each 

product. The chemicals used in each product may be used in conjunction with the 

formulations data (described in the previous bullet) to discern the chemicals used in each 

formulation. The manufacturer of each product will also be included. 

• Number of products reported for a given product function and the frequency with which a 

product function is reported in the formulations data. The product function with the 

greatest number of products and the product function that is most often used in 

formulations. 

• Number of products and chemicals for each type of formulation. The chemicals and products 

for various types of formulations and a description of the average number of products and 

chemicals for each formulation type, as well as the sample size for each population and 

common product functions for each formulation type. 

• Typical loadings for each group of products of a given product function and for each fluid 

formulation type. The typical proportion of a product in a formulation. Typical loading 

values (e.g., gallons per thousand gallons) indicate an amount or volume of a product 

added to a volume of fracturing fluids rather than an accurate representation of the 

concentration of a particular product or the chemical constituents of a product in a fluid 

formulation. 

Information provided by the companies relating to surface spills of hydraulic fracturing fluids and 

chemicals has been compiled, resulting in a table of specific spill incidences. The table includes 

information on the location, composition, volume, cause, and any reported impacts of each spill. 

This information will be used in the larger analysis of surface spills reported in federal and state 

databases (Section 3.2). 

Well Injection. The EPA requested information regarding the hydraulic fracturing service 

companies’ procedures for establishing well integrity, procedures used during well injections, and 

response plans to address unexpected circumstances (e.g., unexpected pressure changes during 

injection). Information provided by the companies will be used to write a narrative description of 

the range of operations conducted by this sample of service companies. 

Flowback and Produced Water. Although this information was not requested, the EPA received 

some documents and information that referenced flowback and produced water, including policies, 

practices, and procedures employed by companies to determine estimated volumes and 

management options. The EPA has reviewed this information as well as information relevant to the 

42



frequency, severity, and causes of flowback and produced water spills and the composition of 

hydraulic fracturing wastewaters. The outputs of the analysis will include the following: 

• Reported spills of flowback and produced water. Information on the composition of the fluid 

spilled, the volume spilled, the reported cause of the spill, and any reported impacts to 

nearby water resources. This information will be integrated into the larger analysis of 

surface spills reported in federal and state databases (see Section 3.2). 

• Reported compositions of hydraulic fracturing wastewater. Information on the chemical and 

physical properties of hydraulic fracturing wastewater, such as the identities of analytes of 

interest and reported concentration ranges. To the extent possible, this information will be 

organized according to geologic and geographic location as well as time after fluid 

injection. 

• Flowback and produced water management. Where possible, information about the role of 

hydraulic fracturing service companies in handling flowback and produced water will be 

described. 


Preliminary data analyses of service company operations, water acquisition, chemical mixing, and 

flowback and produced water has been completed and the analysis of well injection information 

has begun. The EPA has met with representatives from each of the nine hydraulic fracturing service 

companies to discuss their responses to the September 2010 information request. Information 

gathered during these meetings has been used to inform the data analysis and to ensure that 

confidential information is protected. As of September 2012, the EPA continues to clarify the 

information reported and to work with the nine hydraulic fracturing service companies to release 

information originally designated as CBI without compromising trade secrets. 

Service Company Operations. As a group, the nine service companies reported that they 

hydraulically fractured 24,925 wells in the United States in 2009 and 2010. The companies 

reported the number of wells per county, which is displayed for all companies in Figure 10. 

43



Figure 10. Locations of oil and gas production wells hydraulically fractured between September 2009 and October 

2010. The information request to service companies (September 2010) resulted in county-scale locations for 24,925 

wells. The service company wells represented in this map include only 24,879 wells because the EPA did not receive 

locational information for 46 of the 24,925 reported wells. (ESRI, 2010a, b; US EPA, 2011a) 

Chemical Mixing. The service companies reported a total of 114 example formulations and 1,858 

unique producets, which consist of 677 unique chemicals, used by the service companies between 

September 2005 and 2010. 29 Table 20 shows the number of formulations, products, and chemicals 

reported by each of the nine service companies; the totals for products and chemical constituents in 

Table 20 reflect use by multiple companies and are therefore greater than the sum of unique 

products and chemical constituents. The formulations reported to the EPA are not comprehensive, 

as each service company chose them as examples of the fluids they use. 

29 Products and chemical constituents noted here are unique and may have been reported multiple times by the service 

companies. 

44



Table 20. Formulations, products, and chemicals reported as used or distributed by the nine service companies 

between September 2005 and September 2010. 

Company Formulations Products* Chemical Constituents † 

BJ Services 37 401 118 

Key Energy Services 16 180 119 

Halliburton 15 450 304 

RPC 13 182 128 

Schlumberger 11 110 61 

Patterson-UTI Energy 10 67 67 

Weatherford International 6 214 180 

Complete Production Services 3 122 92 

Superior Well Services 3 312 117 

* Companies reported examples of formulations, which did not contain all of the products reported to the EPA. 

† 

Not all products have reported chemicals. 

Non-confidential hydraulic fracturing chemicals reported by the companies appear in Appendix A, 

along with chemicals reported from publicly available sources. 

Well Injection. Seven service companies reported 231 protocols to the EPA. The protocols describe 

the procedures used by the companies for many aspects of field and laboratory work, including site 

and infrastructure planning, chemical mixing and design of fracturing fluid formulations, health and 

safety practices, well construction, and hydraulic fracturing. The EPA is analyzing the information 

to assess how hydraulic fracturing service companies use SOPs, to better understand how well 

integrity is established prior to fracturing, and to evaluate procedures used during well injection. 

Flowback and Produced Water. Data provided by the companies indicate that the company 

conducting the fracturing is often not the same company that manages the flowback process. Five of 

the companies responded that they do not provide flowback services, although one of these 

companies provides analytical support to operators for the testing of flowback water for potential 

reuse. Two of the nine stated that they provide flowback services independent of their hydraulic 

fracturing services. For another two companies, the EPA received no information clearly describing 

role regarding flowback services. Only one company provided detailed information on flowback 

management. 


All analyses will undergo a QA review before being compiled in a final report. The EPA will continue 

to work with each of the nine companies to determine how best to summarize the results so that 

CBI is protected while providing information in a transparent manner. 


The QAPP for the analysis of data received from nine service companies, “Analysis of Data Received 

from Nine Hydraulic Fracturing (HF) Service Companies (Version 1),” was approved on August 1, 

2012 (US EPA, 2012h). A TSA on the work was conducted by designated EPA QA Manager on 

August 28, 2012, to review the methods being used and work products being developed with the 

data. The work accurately reflected what is described in the QAPP, and no corrective actions were 

45



identified. In addition, the EPA’s contractor, Eastern Research Group, has been involved with 

collecting and compiling data submitted from the nine hydraulic fracturing service companies. 

Eastern Research Group’s QAPP was approved on January 19, 2011 (Eastern Research Group Inc., 

2011). 

3.4. Well File Review 


The well file review provides an opportunity to assess well construction and hydraulic fracturing 

operations, as reported by the companies that own and operate oil and gas production wells. 

Results from the review will inform answers to the secondary research questions listed in Table 21. 

Table 21. Secondary research questions addressed by the well file review research project. 






Wastewater treatment and 

waste disposal 


• How much water is used in hydraulic fracturing operations, and 

what are the sources of this water 

• What is currently known about the frequency, severity, and 

causes of spills of hydraulic fracturing fluids and additives 

• What are the identities and volumes of chemicals used in 

hydraulic fracturing fluids, and how might this composition vary 

at a given site and across the country 

• If spills occur, how might hydraulic fracturing chemical additives 

contaminate drinking water resources 

• How effective are current well construction practices at 

containing gases and fluids before, during, and after fracturing 

• Can subsurface migration of fluids and gases to drinking water 

resources occur and what local geologic or man-made features 

may allow this 

• What is currently known about the frequency, severity, and 

causes of spills of flowback and produced water 

• What is the composition of hydraulic fracturing wastewaters, 

and what factors might influence this composition 

• If spills occur, how might hydraulic fracturing wastewater 


• What are the common treatment and disposal methods for 

hydraulic fracturing wastewaters, and where are these methods 

practiced 


The process of planning, designing, permitting, drilling, completing, and operating oil and gas wells 

involves many steps, all of which are ultimately controlled by the company that owns or operates 

the well, referred to as the “operator.” Assisting the operator are service companies that provide 

specialty services, such as seismic surveys, lease acquisition, road and pad building, well drilling, 

logging, cementing, hydraulic fracturing, water and waste hauling, and disposal. Some operators 

can perform some of these services on their own and some rely exclusively on service companies. 

During the development and production of oil and gas wells, operators receive documentation from 

service companies about site preparation and characteristics, well design and construction, 

hydraulic fracturing, oil and gas production, and waste management. Operators typically maintain 

46



much of this information in an organized file, which cumulatively represents the history of the well. 

The EPA refers to this file as a “well file.” Some of the information in a well file may be required by 

law to be reported to state oil and gas agencies, and some of the information may be considered CBI 

by the operator. 

For this project, the EPA is scrutinizing actual well files from hydraulic fracturing operations in 

different geographic areas that are operated by companies of various sizes. These wells include 

vertical, horizontal, and deviated wells that produce oil, gas, or both from differing geological 

environments. This review is providing information that can be used to identify practices that may 

impact drinking water resources. 


While a portion of the data needed for this project is reported to state oil and gas agencies, the 

complete dataset is available only in the well files compiled by oil and gas operators. 30 Further, 

different states have different reporting requirements. As a result, the EPA selected 350 well 

identifiers believed to represent oil and gas production wells hydraulically fractured by the nine 

hydraulic fracturing service companies and requested the corresponding well files from operators 

associated with those wells. 31 This section describes the process used by the EPA to select well files 

for review, the information requested, and the planned analyses. 

Well File Selection. The EPA used a list of hydraulically fractured oil and gas wells provided to the 

agency by the nine hydraulic fracturing service companies (referred to hereafter as the “service 

company well list”) to select 350 specific well identifiers associated with nine oil and gas 

operators. 32 The service company well list obtained by the EPA contains 24,925 well identifiers 

associated with wells that were reported to have been hydraulically fractured between September 

2009 and October 2010 (Figure 10) and identifies 1,146 oil and gas operators. This compiled list 

includes, for each well, a well identifier, the operator’s name, and the well’s state and county 

location. 

Counties containing the 24,925 well identifiers were grouped into four geographic regions 

according to a May 9, 2011, map of current and prospective shale gas plays within the lower 48 

states (US EIA, 2011c). 33 If any portion of a county was within one of the shale gas plays defined on 

the map, the entire county was assigned to that shale play and the corresponding geographic 

region. The four regions—East, South, West, and Other—are shown in Figure 11 with the 

corresponding number of wells in each region. Counties outside the shale gas plays were grouped 

30 The EPA analyzed several state oil and gas agency websites and estimated that it would find less than 15% of the 

necessary data from websites to answer the research questions. 

31 Oil and gas production wells are generally assigned API numbers by state oil and gas agencies, a unique 10-digit 

number. Wells may also be commonly identified by a well name that is designated by the operator. The EPA considers 

both of these to be well identifiers. 

32 The EPA used the service company well list because it is unaware of the existence of a single list showing all oil and gas 

production wells in the United States, their operators, and whether each well has been hydraulically fractured. 

33 Wells within a designated shale play on the map are not guaranteed to be producing from that shale; they could be 

producing from rock formations within the same stratigraphic column. 

47



into the Other region, which includes areas where oil and gas is produced from a variety of rock 

formations. 34 This grouping process allowed the EPA to select wells that reflect the geographic 

distribution of hydraulically fractured oil and gas wells. 

A list of operators and their corresponding total well count was sorted by well count from highest 

to lowest. Operators with fewer than 10 well identifiers were removed, resulting in a final list of 

266 operators and 22,573 wells. The resulting operators were categorized as “large,” “medium,” or 

“small.” Large operators were defined as those that accounted for the top 50% of the well 

identifiers on the list, medium operators for the next 25% and small operators for the last 25%. As 

a result, there were 17 large operators, 86 medium operators, and 163 small operators. To ensure 

that the final selected well identifiers would have geographic diversity among large operators, each 

large operator was assigned to one geographic region that contained a large number of its well 

identifiers. 

One large operator was randomly chosen from each of the regions (i.e., one large operator from 

each of the East, South, West, and Other regions), for a total of four large operators. Two medium 

operators and three small operators were also chosen, with no preference for geographic region. 

This resulted in the selection of nine operators: Clayton Williams Energy, ConocoPhillips, EQT 

Production, Hogback Exploration, Laramie Energy, MDS Energy, Noble Energy, SandRidge Energy, 

and Williams Production. 

34 Forty-six well identifiers had unknown counties and have been included in the Other region for the purposes of this 

analysis. 

48



Figure 11. Locations of oil and gas production wells hydraulically fractured from September 2009 through October 

2010. The information request to service companies (September 2010) resulted in county-scale locations for 24,925 

wells. The service company wells are represented above as regional well summaries and summarize only 24,879 

wells because the EPA did not have locational information for 46 of the 24,925 reported wells. (ESRI, 2010a, b; US 

EPA, 2011a) 

The nine operators were associated with 2,455 well identifiers. The EPA initially chose 400 of those 

2,455 well identifiers to request the associated well files for its analysis. The selection of 400 well 

identifiers required balancing goals of maximizing the geographic diversity of wells and maximizing 

the precision of any forthcoming statistical estimates. The well identifiers were chosen using an 

optimization algorithm that evaluated the statistical precision given different allocations across 

operating company/shale play combinations. The algorithm identified a solution given four 

constraints: 

49



• Select all well identifiers for the three small operators whose total number of well 

identifiers was fewer than 35. For all other operators, keep the number of selected well 

identifiers between 35 and 77. 

• Have at least two well identifiers (or one if there is only one) from each combination of a 

large operator and geographic region. 

• Keep the regional distribution of sampled well identifiers close to the regional distribution 

of all 24,925 well identifiers on the initial service company well list. 

• Keep the expected sampling variance due to unequal weights relatively small. 

Due to resource and time constraints, the EPA subsequently decided to review 350 well files, so 50 

of the 400 selected well identifiers were randomly removed. This sample size is large enough to be 

considered reasonably representative of the total number of wells hydraulically fractured by the 

nine service companies in the United States during the specified time period. 

Data Requested. An information request letter was sent in August 2011 to the nine operators 

identified above, asking for 24 distinct items organized into five topic areas: (1) geologic maps and 

cross sections; (2) drilling and completion information; (3) water quality, volume, and disposition; 

(4) hydraulic fracturing; and (5) environmental releases. 35 Table 22 shows the potential 

relationship between the five topic areas and the stages of the hydraulic fracturing water cycle. 

Table 22. The potential relationship between the topic areas in the information request and the stages of the 

hydraulic fracturing water cycle. 

Information Request Topic Areas 

Water Cycle Geologic Maps Drilling and Water Quality, 

Stage 

Hydraulic 

and Cross - Completion Volume, and 

Fracturing 

Sections Information Disposition 

Water acquisition 

Environmental 

Releases 

Chemical mixing 

Well injection 

Flowback and 

produced water 

Wastewater 

treatment and 


 

Well File Review and Analysis. The EPA received responses to the August 2011 information request 

from each of the nine operators. Data and information contained in the well files is being extracted 

from individual well files and compiled in a single Microsoft Access database. All data in the 

database are linked by the well’s API number; this process is described in more detail in the QAPP 

for this research project (US EPA, 2012j). 

 

 

35 See the text of the information request for the specific items requested under each topic area. The information request 

can be found at http://www.epa.gov/hfstudy/August_2011_request_letter.pdf. 

50



Information in the database is being used to design queries that will inform answers to the research 

questions listed in Table 21. Examples of queries being designed include: 

• What sources and volumes of water are used for hydraulic fracturing fluids 

• How many well files contain reports of chemicals spilled during hydraulic fracturing, and 

do the reports show whether the spills led to any impacts to drinking water resources 

• How many wells have poor cement bonds immediately above the uppermost depth being 

hydraulically fractured This may indicate that the cement sheath designed to isolate the 

target zone being stimulated may fail, potentially leading to gas and fluid migration up the 

wellbore. 

• How many well files contain reports of flowback or produced water spilled, and do the 

reports show whether the spills lead to any impacts to drinking water resources 

• What are the reported treatment and/or disposal methods for the wastewater generated 

from hydraulic fracturing 


Of the 350 well identifiers selected for analysis, the EPA received information on 334 wells. One of 

these was never drilled, ultimately providing the EPA with well files for 333 drilled wells. 36 Table 

23 lists the number of wells for which valid data were provided by each operator and their 

designated company size. 

Table 23. Number of wells for which data were provided by each operator. Company size, as determined for this 

analysis, is also listed. The nine operators provided data on a total of 333 oil and gas production wells. 

Operator Company Size Number of Wells 

Noble Energy Large 67 

ConocoPhillips Large 57 

Williams Production Large 50 

Clayton Williams Energy Medium 36 

SandRidge Energy Medium 35 

EQT Production Large 29 

MDS Energy Small 24 

Laramie Energy Small 21 

Hogback Exploration Small 14 

Total 333 

Figure 12 shows a map of the 333 well locations. The well locations are distributed within 13 

states: Arkansas, Colorado, Kentucky, Louisiana, New Mexico, North Dakota, Oklahoma, 

Pennsylvania, Texas, Utah, Virginia, West Virginia, and Wyoming. 

36 Sixteen of the 350 well identification numbers were not valid for this project: 13 were duplicate entries, one was in 

Canada, one was not a well, and one was not actually owned by the selected operator. In total, roughly 5% of the 350 well 

identifiers chosen for review by the EPA do not correspond to oil and gas wells that have been hydraulically fractured. 

This provides a rough assessment of the accuracy of the original data received from the nine hydraulic fracturing service 

companies (the service company well list). 

51



Figure 12. Locations of 333 wells (black points) selected for the well file review. Also shown are the locations of oil 

and gas production wells hydraulically fractured from September 2009 through October 2010. The information 

request to service companies (September 2010) resulted in county-scale locations for 24,925 wells. The service 

company wells are represented above as regional well summaries and summarize only 24,879 wells because the 

EPA did not have locational information for 46 of the 24,925 reported wells. (ESRI, 2010a, b; US EPA, 2011a, d) 

The EPA received approximately 9,670 electronic files in response to the August 2011 information 

request. The amount of information received varied from one well file to another. Some well files 

included nearly 

all 

of the 

information requested, while others were missing 

information 

on 

entire 

topical areas. 

Some of the 

data received 

were 

claimed 

as CBI 

under 

TSCA. 

The EPA 

has 

contacted 

all 

nine of the oil and gas operators 

to clarify 

its understanding 

of the data, where 

necessary, and to 

discuss 

how to 

depict 

the 

well 

file 

data while still protecting confidential information. 

The analyses 

described 

in the previous 

section 

are 

being 

performed 

according 

to 

CBI procedure 

s (US 

EPA, 

2003b) 

, and 

the 

results 

are considered 

CBI 

until 

determinations 

are 

made 

or until data 

masking has 

been done to 

prevent 

release of CBI 

information. 

The EPA is extracting available data from the well files that can be used to answer research 

questions related to all stages of the hydraulic fracturing water cycle. As of September 2012, the 

52



EPA had extracted, and continues to extract, the following available information from all of the well 

files: 

• Open-hole log analysis of lithology, hydrocarbon shows, and water salinity 

• Chemical analyses of various water samples 

• Well construction data 

• Cement reports 

• Cased-hole logs, including identifying cement tops and bond quality 

Other data to be extracted includes the following: 

• Source of water used for hydraulic fracturing 

• Well integrity pressure testing 

• Fluid volumes injected during well stimulation and type and amount of additives and 

proppant used 

• Pressures used during hydraulic fracturing 

• Fracture growth data including that predicted and that observed 

• Flowback and produced water data following hydraulic fracturing including volume, 

disposition, and duration 

The EPA is creating queries on the extracted data that are expected to determine whether drinking 

water resources were protected from hydraulic fracturing operations. The results of these queries 

may indicate the frequency and variety of construction and fracturing techniques that could lead to 

impacts on drinking water resources. The results may provide, but may not be limited to, 

information on the following: 

• Sources of water used for hydraulic fracturing 

• Vertical distance between hydraulically fractured zones and the top of cement sheaths 

• Quality of cementing near hydraulic fracturing zones, as determined by a cement bond 

index 

• Number of well casing intervals left uncemented and whether there are aquifers in those 

intervals 

• Distribution of depths of hydraulically fractured zones from the surface 

• Frequency with which various tests are conducted, including casing shoe pressure tests 

and casing pressure tests 

• Types of rock formations hydraulically fractured 

• Types of well completions (e.g., vertical, horizontal) 

• Types and amounts of proppants and chemicals used during hydraulic fracturing 

• Amounts of fracture growth 

53



• Distances between wells hydraulically fractured and geologic faults 

• Proportions of fluid flowed back to the surface following hydraulic fracturing and the 

disposition of the flowback 


Additional Database Analysis. The EPA plans to conduct further reviews of the well files to extract 

information relating to water acquisition for hydraulic fracturing, hydraulic fracturing fluid 

injection, and wastewater management. 

Statistical Analysis. Once the data analysis has been completed, where possible, extrapolation of the 

results will be performed to the sampled universe of 24,925 wells, using methods consistent with 

published statistical practices (Kish, 1965). 

Confidential Business Information. The EPA is working with the oil and gas operators to determine 

how best to summarize the results so that CBI is protected while upholding the agency’s 

commitment to transparency. 


The EPA and its contractor, The Cadmus Group, Inc., are evaluating the well file contents. The QAPP 

associated with this project, “National Hydraulic Fracturing Study Evaluation of Existing Production 

Well File Contents (Version 1),” was approved on January 4, 2012 (US EPA, 2012j). A supplemental 

QAPP developed by Cadmus was approved on March 6, 2012 (Cadmus Group Inc., 2012b). Each 

team involved in the well file review underwent a separate TSA by the designated EPA QA Manager 

to ensure compliance with the approved QAPP. The audits occurred between April and August of 

2012. No corrective actions were identified. 

Westat, under contract with the EPA, is providing statistical support for the well file analysis. A 

QAPP, “Quality Assurance Project Plan v1.1 for Hydraulic Fracturing,” was developed by Westat and 

approved on July 15, 2011 (Westat, 2011). 

3.5. FracFocus Analysis 


Extracting data from FracFocus allows the EPA to gather publicly available, nationwide information 

on the water volumes and chemicals used in hydraulic fracturing operations, as reported by oil and 

gas operating companies. Data compiled from FracFocus are being used to help inform answers to 

the research questions listed in Table 24. 

Table 24. Secondary research questions addressed by extracting data from FracFocus, a nationwide hydraulic 

fracturing chemical registry. 





How much water is used in hydraulic fracturing operations, and what 

are the sources of this water 

What are the identities and quantities of chemicals used in hydraulic 

fracturing fluids, and how might this composition vary at a given site 

and across the country 

54




At the time the draft study plan was written in early 2011, the Ground Water Protection Council 

and the Interstate Oil and Gas Compact Commission jointly launched a new national registry for 

chemicals used in hydraulic fracturing, called FracFocus (http://www.fracfocus.org; (GWPC, 

2012b)). This registry, which has become widely accepted as the national hydraulic fracturing 

chemical registry, is an online repository where oil and gas well operators can upload information 

regarding the chemical compositions of hydraulic fracturing fluids used in specific oil and gas 

production wells. It has become one of the largest sources of data and information on chemicals 

used in hydraulic fracturing and may be the largest single source of publicly disclosed data for these 

chemicals. The registry also contains information on well locations, well depth, and water use. 

Confidential business information is not disclosed in FracFocus to protect proprietary or sensitive 

information. 

FracFocus began as a voluntary program on January 1, 2011. Since its introduction, the amount of 

data in FracFocus has been steadily increasing. As of May 2012, the registry contained information 

on nearly 19,000 wells for which hydraulic fracturing fluid disclosures were entered (GWPC, 

2012b). Seven states require operators to use FracFocus to report the chemicals used in hydraulic 

fracturing operations. In addition, many states are expected to pass or are working on legislation to 

require reporting with FracFocus. 37 

Although it represents neither a random sample nor a complete representation of the wells 

fractured during this time period, the number of well disclosures in FracFocus may constitute a 

large portion of the number of wells hydraulically fractured in the United States for this time 

period. For comparison, nine hydraulic fracturing service companies reported that nearly 25,000 

wells were fractured between September 2009 and October 2010, as described in Section 3.3. 

This analysis is gathering information on water and chemical use in hydraulic fracturing operations 

and attempts to answer the following questions: 

• What are the patterns of water usage in hydraulic fracturing operations reported in 

FracFocus 

• What are the different sources of water reported in FracFocus, and is it possible to 

determine the relative proportions by volume or mass of these different sources of water 

• What are the identities of chemicals used in hydraulic fracturing fluids reported in 

FracFocus 

• Which chemicals are reported most often in FracFocus 

• What is the geographic distribution of the most frequently reported chemicals in 

FracFocus 

37 The seven states requiring disclosure to FracFocus are Colorado, Louisiana, Montana, North Dakota, Oklahoma, 

Pennsylvania, and Texas. As of September 2012, the EPA is aware of eight more states considering the use of FracFocus: 

Alaska, California, Illinois, Kansas, Kentucky, New Mexico, Ohio, and West Virginia. 

55



3.5.3. FracFocus Data 

All data in FracFocus are entered by oil and gas companies that have agreed to “disclose the 

information in the public interest” (GWPC, 2012b). The Ground Water Protection Council, the 

organization that administers the registry, makes no specific claim about data quality in FracFocus. 

There is considerable variability in the posted data because they are uploaded by many different 

companies, including operator and service companies. Although FracFocus uses some built-in QA 

checks during the data upload process, several data quality issues are not addressed by these 

protocols. As a result, the EPA conducted a QA review of the data, as described in the next section. 

Data in FracFocus are presented in individual PDF formats for individual wells; an example PDF is 

provided in Figure 13. Individual wells can be searched using a Google Maps application 

programming interface. In addition, well disclosure records can be searched by state, county, and 

operator. Results are returned by listing links to individual PDF files. Because only single well 

disclosure records are downloadable, systematic analysis of larger datasets is more challenging. 

Data must be extracted and transformed into more appropriate formats (e.g., a Microsoft Access 

database) for this type of analysis. 

Data in FracFocus can be classified into two general types: well or “header” data and chemical- or 

ingredient-specific data. Header data describe information about each well, including the fracture 

date, API number, operator, well location, and total fluid volume, as shown in Figure 13. Chemicalspecific 

data provide the trade names of ingredients, the chemicals found in these ingredients, and 

the concentrations used in the hydraulic fracturing fluid. Some well disclosures include information 

on the type or source of water in the chemical-specific data table. 

The EPA has downloaded data in FracFocus on wells hydraulically fractured during 2011 and the 

beginning of 2012. It is beyond the scope of this project to evaluate the quality or 

representativeness on a national scale of the data submitted to FracFocus by oil and gas operators. 

The data cannot be assumed to be a complete or statistically representative of all hydraulically 

fractured wells. However, because FracFocus contains several thousands of well disclosures 

distributed throughout the United States, the EPA believes that the data in FracFocus are generally 

indicative of hydraulic fracturing activities during the time period covered. Therefore, it may be 

possible to find geographic patterns of occurrence or usage, including volume of water, frequency 

of chemical usage, and amounts of chemicals used, assuming that data in FracFocus meet quality 

requirements. 

56



Figure 13. Example of data disclosed through FracFocus. Data included in each PDF can be classified into two general types: well or “header” data and chemical- or 

ingredient-specific data. Header data are located in the top table, and ingredient-specific data are found in the bottom table. Provided by Ground Water Protection 

Council. 

57




Data were first extracted from the FracFocus website, put into more appropriate formats for QA 

review, and then organized into a final database for analysis of fracturing fluid chemicals and water 

usage and source. The geographic coordinates provided for wells will be linked to both the chemical 

and water data (Figure 13) to determine if regional patterns exist. A QA review was performed 

following the data extraction and initial processing. The last stage of this project involves the 

quantitative analyses of the QA-reviewed data. These three stages are described in more detail 

below. 

3.5.4.1. Data Extraction and Organization 

Records for 12,306 wells hydraulically fractured from January 1, 2011, through February 27, 2012, 

were extracted from FracFocus PDF files and converted to XML using Adobe Acrobat Pro X 

software. Header- and chemical-specific data were mined from the XML files using text recognition 

software (Cadmus Group Inc., 2012b). 38 Using this technique, data representing 12,173 (>98% of 

the downloaded records) well records were compiled. Once fully processed, the data records were 

organized into two working files: one file containing header data that included well-specific 

geography, fracturing fluid volume, and well depth and one file containing chemical-specific data. 

The working files are linked by unique well identification numbers assigned by the contractor that 

developed the database for EPA. 

3.5.4.2. Data Quality Assurance Review 

Manual and automated methods were used to assess the data quality and make necessary 

adjustments. Records in the header data working file were flagged according to the following 

criteria: duplicate records, as identified by identical API numbers; fracture dates outside the 

January 1, 2011, to February 27, 2012, time period; anomalously large or small volumes of water; 

and anomalously deep or shallow true vertical depths. These records were kept in the working files, 

but flagged in order to exclude them from future analyses. Half of the duplicate records were 

excluded from all queries and analyses. 

Spatial data from the well records include three sources, which can be used to perform quality 

checks: state and county names, latitude and longitude coordinates, and the state and county 

information encoded in the first five digits of the API Well Number (Figure 13). To validate the 

location of the wells, the state and county information from each of the locational fields was 

compared. State and county information (ESRI, 2010a, b) was assigned to the latitude and 

longitude coordinates by spatially joining the data in ArcGIS (ESRI, version 10). Validated spatial 

location was available for 12,163 wells (>99% of records extracted) (Cadmus Group Inc., 2012b). 

Chemical names in the “Ingredients” field of chemical-specific data table were standardized 

according to the CASRN provided in the associated “Chemical Abstract Service Number” field 

38 The text recognition software is highly sensitive to inconsistencies in reporting. If an operator departs from the general 

template when creating the well record, the record will be passed over or data will be extracted incorrectly. The 

contractor was able to convert data from 12,173 of the 12,302 well records into a more useable format (Cadmus Group 

Inc., 2012b). 

58



(Figure 13). As described in Chapter 6, the EPA has compiled and curated a list of chemicals 

reported to be used in hydraulic fracturing fluids from many data sources. This list was used to 

standardize the chemical names provided in FracFocus by matching CASRNs. 39 

Water sources were also identified from the “Ingredients” field. Data were first organized to 

identify wells where water has been listed as a trade name or ingredient and has been used as a 

“carrier” or “base” fluid, excluding records that indicated the water has been used as a solvent for 

hydraulic fracturing chemicals. Additionally, records listing the CASRN for water (7732-18-5) and 

an additive concentration of 70% to 100% were identified. 

3.5.4.3. Data Analysis 

Following the QA review, all data were organized into four data tables: locational data for each well 

disclosure, the original chemical-specific data for each well disclosure, the QA-reviewed chemicalspecific 

data for each well disclosure, and records with water as ingredient. These four tables have 

been imported into a database and linked together using key fields, where they can be used for the 

analyses described below. The raw, pre-QA data values for well disclosures and chemical 

ingredients as they were exported from FracFocus have also been imported into the database for 

baseline reference data to prevent any loss of original operator data. 

Water Acquisition. Total water volume data that meet the QA requirements are being used to 

analyze general water usage patterns on national, state, and county scales of interest. Additional 

queries may be run that analyze water usage by operator and by production type (oil or gas). 

Data will be summarized by water source or type for records where this information is provided. 

Concentrations of water by source type are generally found in the “Maximum Ingredient 

Concentration in HF (hydraulic fracturing) Fluid” field (Figure 13), which is reported as a 

percentage by mass, not percentage by total water volume. In some situations, there will be enough 

i 

information in FracFocus to calculate water volumes by type (V H2O ), whether fresh water (e.g., 

surface water) or non-fresh water (e.g. recycled/produced, saline, seawater or brine). Given the 

FracFocus-reported total water volume (V total H2O ) (US gallons) and assuming that volumes are 

effectively additive, and where n is the number of water types, 

total 

V ≅ ∑ n i 

H2O i=1 V H2O (1) 

using the FracFocus-reported maximum water concentration in the hydraulic fracturing fluid 

i 

(percent by mass for each water type, x H2O ), and assuming an average density for each water type 

i 

(ρ H2O ) (lb/US gallons), the volume of each water type is expressed as: 

i 

i 

x H2O 

ρ H2O 

VH2O = i m total (i = 1, n) (2) 

With n equations and n unknowns represented by equations (1) and (2), the unknown total mass of 

the hydraulic fracturing fluid (m total) (lb) can be calculated: 

39 CASRNs not already found on the EPA’s list of chemicals reported to be used in hydraulic fracturing fluids were added 

to the list following the process outlined in Chapter 6. 

59



total 

V H2O 

mtotal = i (3) 

∑n 

x H2O 

i=1 

ρ i 

H2O 

i 

and the volume of each water type (V H2O ) back-calculated using equation (2). 40 

This calculation can only be made in the situation where the density of the fluid is known or 

reported. For example, in the situation where a FracFocus ingredient is clearly labeled fresh 

(surface) water and carrier or base fluid, a water density may be assumed between 8.34 lb/US 

gallon at 32 °F and 8.24 lb/US gallon at 100 °F (Lide, 2008). In other situations, the density for the 

carrier or base fluid may be reported in the FracFocus comment field. 

Chemical Usage. Queries of the FracFocus data will include the total number of unique chemical 

records nationally, by state, per production type (oil or gas), fracture date, and operator 

represented. Additionally, the data may be queried to identify the frequency or number of well 

disclosures in which each chemical is used nationally, by state, per production type, within a 

fracture date range, and by operator represented. Lists of the top 20 to 30 most frequently used 

chemicals in hydraulic fracturing are likely to be generated at the nation, region, or state level. 

Some of the most frequently occurring chemicals will be mapped to show distribution of 

occurrence. Since chemicals claimed as CBI or proprietary do not have to be reported in FracFocus, 

the number of chemicals disclosed is likely to be lower than the total number of chemicals used. 


The data have been extracted from FracFocus, reviewed for quality issues, and organized in a 

database for analysis. Draft queries have been developed for water usage and chemical frequency 

occurrence nationwide using the database. Preliminary analyses have been conducted as of 

November 2012. Table 25 summarizes, by state, the well data that were downloaded from 

FracFocus in early 2012. 

Table 25. Number of wells, by state, with data in FracFocus as of February 2012. These data represent wells 

fractured and entered into FracFocus between January 1, 2011, and February 27, 2012. 

State 

Number of Wells 

Alabama 54 

Alaska 24 

Arkansas 807 

California 79 

Colorado 2,307 

Kansas 22 

Louisiana 621 

Mississippi 1 

Montana 28 

New Mexico 421 

State 

Number of Wells 

North Dakota 359 

Ohio 11 

Oklahoma 414 

Pennsylvania 1,050 

Texas 4,859 

Utah 409 

Virginia 23 

West Virginia 93 

Wyoming 591 

Total 12,173 

40 The EPA recognizes that volume is not a conserved quantity and estimates that the error introduced by assuming that 

volumes are additive is, in this case, negligible when compared to expected volume and density reporting errors. 

60



During the QA review of the data, the EPA identified 422 pairs of potential duplicate well disclosure 

records (844 total records). A total of 277,029 chemicals were reported in all of the well disclosure 

records. This number includes chemicals listed multiple times (either for the same well or in many 

wells) and 12,464 instances where “water” was listed as an ingredient in the chemical-specific data 

table. The QA review of the chemicals identified 347 unique ingredients that match the EPA CASRN 

list of chemicals and approximately 60 CASRNs that were not previously known to be used in 

hydraulic fracturing fluids. One hundred eighty-four well records had ingredient lists that fully 

matched the EPA CASRN list. Chemical entries in FracFocus that contained “CBI,” “proprietary,” or 

“trade secret” as an ingredient were only 1.3% (3,534 of 277,029) of all chemical ingredients 

reported in FracFocus. Operators reported at least one chemical ingredient as “CBI,” “proprietary,” 

or “trade secret” in 1,924 well records. 

Water was identified as a carrier or base fluid in 10,700 well records (88% of the 12,173 well 

records successfully extracted from FracFocus). Seven categories of source water were identified: 

fresh, surface, sea, produced, recycled, brine, and treated. Definitions for the categories are not 

provided by operators or FracFocus and some categories appear to overlap or may be synonymous. 

Only 1,484 well records identified a water source for those wells that used water as a carrier or 

base fluid. 


The EPA will complete its analysis of the FracFocus data that have already been downloaded. In 

addition, the EPA plans to complete another data download in order to obtain a second year’s 

worth of data. Once the second round of data has been extracted, the EPA will conduct a QA review 

and data analysis similar to the one described for the first round of downloaded data. 


The EPA and its contractor, The Cadmus Group, Inc., are extracting and analyzing data from 

FracFocus. The QAPP associated with this project, “Analysis of Data Extracted from FracFocus 

(Version 1),” was approved in early August 2012 (US EPA, 2012g). A TSA of the analysis was 

conducted by the designated EPA QA Manager shortly after on August 15, 2012; no corrective 

actions were identified. A supplemental QAPP developed by Cadmus was approved March 6, 2012 

(Cadmus Group Inc., 2012b). 

61



4. Scenario Evaluations 

The objective of this approach is to use computer models to explore hypothetical scenarios across 

the hydraulic fracturing water cycle. The models include models of generic engineering and 

geological scenarios and, where sufficient data are available, models of site-specific or regionspecific 

characteristics. This chapter includes progress reports for the following projects: 

4.1. Subsurface Migration Modeling....................................................................................................................... 62 

Numerical modeling of subsurface fluid migration scenarios that explore the potential for 

gases and fluids to move from the fractured zone to drinking water aquifers 

4.2. Surface Water Modeling...................................................................................................................................... 75 

Modeling of concentrations of selected chemicals at public water supplies downstream from 

wastewater treatment facilities that discharge treated hydraulic fracturing wastewater to 

surface waters 

4.3. Water Availability Modeling.............................................................................................................................. 80 

Assessment and modeling of current and future scenarios exploring the impact of water usage 

for hydraulic fracturing on drinking water availability in the Upper Colorado River Basin and 

the Susquehanna River Basin 

4.1. Subsurface Migration Modeling 

Lawrence Berkeley National Laboratory (LBNL), in consultation with the EPA, will simulate the 

hypothetical subsurface migration of fluids (including gases) resulting from six possible 

mechanisms using computer models. The selected mechanisms address the research questions 

identified in Table 26. 

Table 26. Secondary research questions addressed by simulating the subsurface migration of gases and fluids 

resulting from six possible mechanisms. 




• How effective are current well construction practices at 

containing gases and fluids before, during, and after fracturing 

• Can subsurface migration of fluids or gases to drinking water 

resources occur and what local geologic or man-made features 

may allow this 


Stakeholders have expressed concerns about hydraulic fracturing endangering subsurface drinking 

water resources by creating high permeability transport pathways that allow hydrocarbons and 

other fluids to escape from hydrocarbon-bearing formations (US EPA, 2010b, d, e, f, g). Experts 

continue to debate the extent to which subsurface pathways could cause significant adverse 

consequences for ground water resources (Davies, 2011; Engelder, 2012; Harrison, 1983, 1985; 

Jackson et al., 2011; Myers, 2012a, b; Osborn et al., 2011; Warner et al., 2012). The segment of the 

population that receives drinking water from private wells may be especially vulnerable to health 

impacts from impaired drinking water. Unlike water distributed by public water systems, water 

62



from private drinking water wells is not subject to National Primary Drinking Water Regulations, 

and water quality testing is at the discretion of the well owner. 

Lawrence Berkeley National Laboratory, in coordination with the EPA, is using numerical 

simulations to investigate six possible mechanisms that could lead to upward migration of fluids, 

including gases, from a shale gas reservoir and the conditions under which such hypothetical 

scenarios may be possible. The possible mechanisms include: 

• Scenario A (Figure 14): Defective or insufficient well construction coupled with excessive 

pressure during hydraulic fracturing operations results in damage to well integrity during 

the stimulation process. A migration pathway is then established through which fluids 

could travel through the cement or area near the wellbore into overlying aquifers. In this 

scenario, the overburden is not necessarily fractured. 

• Scenario B1 (Figure 15): Fracturing of the overburden because inadequate design of the 

hydraulic fracturing operation results in fractures allowing fluid communication, either 

directly or indirectly, between shale gas reservoirs and aquifers above them. Indirect 

communication would occur if fractures intercept a permeable formation between the 

shale gas formation and the aquifer. Generally, the aquifer would be located at a more 

shallow depth than the permeable formation. 

• Scenario B2 (Figure 16): Similar to Scenario B1, fracturing of the overburden allows 

indirect fluid communication between the shale gas reservoir and the aquifers after 

intercepting conventional hydrocarbon reservoirs, which may create a dual source of 

contamination for the aquifer. 

• Scenario C (Figure 17): Sealed/dormant fractures and faults are activated by the hydraulic 

fracturing operation, creating pathways for upward migration of hydrocarbons and other 

contaminants. 

• Scenario D1 (Figure 18): Fracturing of the overburden creates pathways for movement of 

hydrocarbons and other contaminants into offset wells (or their vicinity) in conventional 

reservoirs with deteriorating cement. The offset wells may intersect and communicate 

with aquifers, and inadequate or failing completions/cement can create pathways for 

contaminants to reach the ground water aquifer. 

• Scenario D2 (Figure 19): Similar to Scenario D1, fracturing of the overburden results in 

movement of hydrocarbons and other contaminants into improperly closed offset wells 

(or their vicinity) with compromised casing in conventional reservoirs. The offset well 

could provide a low-resistance pathway connecting the shale gas reservoir with the 

ground water aquifer. 

The research focuses on hypothetical causes of failure related to fluid pressure/flow and 

geomechanics (as related to operational and geological conditions and properties), and does not 

extend to investigations of strength of casing and tubing materials (an area that falls within the 

confines of mechanical engineering). Damage to the well casing due to corrosive reservoir fluids 

was one other scenario originally considered. Corrosion modeling requires a detailed chemical 

engineering analysis that is beyond the scope of this project, which focuses on geophysical and 

63



mechanical scenarios, so it is not a scenario pursued for this project. Additionally, hypothetical 

scenarios that would cause failure of well structural integrity (e.g., joint splits) are an issue beyond 

the scope of this study, as they involve material quality and integrity, issues not unique to hydraulic 

fracturing. 

Figure 14. Scenario A of the subsurface migration modeling project. This scenario simulates a hypothetical migration 

pathway that occurs when a defective or insufficiently constructed well is damaged during excessive pressure from 

hydraulic fracturing operations. A migration pathway is established through which fluids could travel through the 

cement or area near the wellbore into overlying ground water aquifers. 

64



Figure 15. Scenario B1 of the subsurface migration modeling project. This hypothetical scenario simulates fluid 

communication, either directly or indirectly, between shale gas reservoirs and ground water aquifers as a result of the 

hydraulic fracturing design creating fractures in the overburden. 

65



Figure 16. Scenario B2 of the subsurface migration modeling project. Similar to B1, this hypothetical scenario 

simulates fluid communication, either directly or indirectly, between shale gas reservoirs and ground water aquifers 

as a result of the hydraulic fracturing design creating fractures in the overburden. The fractures intercept a 

conventional oil/gas reservoir before communicating with the ground water aquifer, which may create a dual source of 

contamination in the aquifer. 

66



Figure 17. Scenario C of the subsurface migration modeling project. This hypothetical scenario simulates upward 

migration of hydrocarbons and other contaminants through sealed/dormant fractures and faults activated by the 

hydraulic fracturing operation. 

67



Figure 18. Scenario D1 of the subsurface migration modeling project. This hypothetical scenario simulates 

movement of hydrocarbons and other contaminants into offset wells in conventional oil/gas reservoirs with 

deteriorating cement due to fracturing of the overburden. The offset wells may intersect and communicate with 

aquifers, and inadequate or failing completions/cement can create pathways for contaminants to reach ground water 

aquifers. 

68



Figure 19. Scenario D2 of the subsurface migration modeling project. Similar to Scenario D1, this hypothetical 

scenario simulates movement of hydrocarbons and other contaminants into offset wells in conventional oil/gas 

reservoirs due to fracturing of the overburden. The offset wells in Scenario D2 are improperly closed with 

compromised casing, which provides a low-resistance pathway connecting the shale gas reservoir with the ground 

water aquifer. 

69




Objectives of the subsurface migration scenario evaluation research project include: 

• Determining whether the hypothetical migration mechanisms shown in Figures 14 

through 19 are physically and geomechanically possible during field operations of 

hydraulic fracturing and, if so, identifying the range of conditions under which fluid 

migration is possible. 

• Exploring how contaminant type, fluid pressure, and local geologic properties control 

hypothetical migration mechanisms and affect the possible emergence of contaminants in 

an aquifer. 

• Conducting a thorough analysis of sensitivity to the various factors affecting contaminant 

transport. 

• Assessing the potential impacts on drinking water resources in cases of fluid migration. 

This research project does not assess the likelihood of a hypothetical scenario occurring during 

actual field operations. 

Computational Codes. The LBNL selected computational codes able to simulate the flow and 

transport of gas, water, and dissolved contaminants concurrently in fractures and porous rock 

matrices. The numerical models used in this research project couple flow, transport, 

thermodynamics, and geomechanics to produce simulations to promote understanding of 

conditions in which fluid migration occurs. 

Simulations of contaminant flow and migration began in December 2011 and identified a number of 

important issues that significantly affected the project approach. More specifically, the numerical 

simulator needed to include the following processes in order to accurately describe the 

hypothetical scenario conditions: 

• Darcy and non-Darcy (Forchheimer or Barree and Conway) flow through the matrix and 

fractures of fractured media 

• Inertial and turbulent effects (Klinkenberg effects) 

• Real gas behavior 

• Multi-phase flow (gas, aqueous, and potentially an organic phase of immiscible substances 

involved in the hydraulic fracturing process) 

• Density-driven flow 

• Mechanical dispersion, in addition to advection and molecular diffusion 

• Sorption (primary and secondary) of ions introduced in hydraulic fracturing-related 

processes and gases onto the grains of the porous media, involving one of three possible 

sorption models (linear, Langmuir, or Freundlich) under equilibrium or kinetic conditions 

70



Thermal differentials between ground water and shale gas reservoirs are substantial and may 

significantly impact contaminant transport processes. Thus, the simulator needed to be able to 

account for the following processes in order to fully describe the physics of the problem: 

• Coupled flow and thermal effects, which affect fluid viscosity, density, and buoyancy and, 

consequently, the rate of migration. 

• Effect of temperature on solubility. Lower temperatures can lead to supersaturation of 

dissolved gases or dissolved solids. The latter can result in halite formation stemming 

from salt precipitation, caused by lower temperatures and pressures as naturally 

occurring brines ascend toward the ground water. Halite precipitation can have a 

pronounced effect on both the specific fractures and the overall matrix permeability. 

There is currently no single numerical model that includes all of these processes. Thus, the LBNL 

chose the Transport of Unsaturated Groundwater and Heat (TOUGH) family of codes 41 (Moridis et 

al., 2008) in combination with the existing modules listed in Table 27 to create a model that better 

simulates the subsurface flow and geomechanical conditions encountered in the migration 

scenarios. 

Table 27. Modules combined with the Transport of Unsaturated Groundwater and Heat (TOUGH) (Moridis et al., 

2008) family of codes to create simulations of subsurface flow and geomechanical conditions encountered in the 

migration scenarios designed by Lawrence Berkeley National Laboratory. 

Module 

Purpose 

Describes the coupled flow of a real gas mixture and heat in geologic 

TOUGH+Rgas* 

media 

Describes the non-isothermal two-phase flow of a real gas mixture and 

TOUGH+RgasH2O* water and the transport of heat in a gas reservoir, including tight/shale 

gas reservoirs 

TOUGH+RGasH2OCont † Describes physics and chemistry of flow and transport of heat, water, 

gases, and dissolved contaminants in porous/fractured media 

Simulates geomechanical behavior of multiple porosity/permeability 

ROCMECH § 

continuum systems and can accurately simulate the evolution and 

propagation of fractures in a formation following hydraulic fracturing 

* (Moridis and Freeman, 2012) 

† 

(Moridis and Webb, 2012) 

§ 

(Kim and Moridis, 2012a, b, c, d, e) 

The TOUGH+ code includes equation-of-state modules that describe the non-isothermal flow of real 

gas mixtures, water, and solutes through fractured porous media and accounts for all processes 

involved in flow through tight and shale gas reservoirs (i.e., gas-specific Knudsen diffusion, gas and 

solute sorption onto the media, non-Darcy flow, salt precipitation as temperature and pressure 

drop in the ascending reservoir, etc.) (Freeman, 2010; Freeman et al., 2011; Freeman et al., 2009a, 

b; Freeman et al., 2012; Moridis et al., 2010; Olorode, 2011). The LBNL paired relevant modules 

with TOUGH+ code: one code, TOUGH+RGasH2OCont (Moridis and Freeman, 2012), addresses the 

41 The TOUGH codes include TOUGH2, T2VOC, TMVOC, TOUGH2-MP, TOUGHREACT, TOUGH+, AND iTOUGH2. More 

information on the codes can be found at http://esd.lbl.gov/research/projects/tough. 

71



physics and chemistry of flow and transport of heat, water, gases, and dissolved contaminants in 

porous/fractured media; a second code, TOUGH+RgasH2O (Moridis and Webb, 2012), describes the 

coupled flow of a gas mixture and water and the transport of heat; a third code, TOUGH+Rgas 

(Moridis and Webb, 2012), is limited to the coupled flow of a real gas mixture and heat in geologic 

media. 

A geomechanical model, ROCMECH, was also coupled with the TOUGH+ code and modules (Table 

27) and describes the interdependence of flow and geomechanics including fracture growth and 

propagation (Kim and Moridis, 2012a, b, c, d, e). The ROCMECH 42 code is designed for the rigorous 

analysis of either pure geomechanical problems or, when fully coupled with the TOUGH+ multiphase, 

multi-component, non-isothermal code, for the simulation of the coupled flow and 

geomechanical system behavior in porous and fractured media, including activation of faults and 

fractures. The coupled TOUGH+ ROCMECH codes allow the investigation of fracture growth during 

fluid injection of water (after their initial development during hydraulic fracturing) using fully 

dynamically coupled flow and geomechanics and were used in a series of fracture propagation 

studies (Kim and Moridis, 2012a, b, c, d, e). The ROCMECH code developed by the LBNL for this 

study includes capabilities to describe both tensile and shear failure based on the Mohr-Coulomb 

model, multiple porosity concepts, non-isothermal behavior, and transverse leak-off (Kim and 

Moridis, 2012a). 

Input Data. Input data supporting the simulations are being estimated using information from the 

technical literature, data supplied by the EPA, and expert judgment. Input data include: 

• Site stratigraphy 

• Rock properties (grain density, intrinsic matrix permeability, permeability of natural 

fracture network, matrix and fracture porosity, fracture spacing and aperture) 

• Initial formation conditions (fracture and matrix saturation, pressures) 

• Gas composition 

• Pore water composition 

• Gas adsorption isotherm 

• Thermal conductivity and specific heat of rocks 

• Parameters for relative permeability 

• Hydraulic fracturing pressure 

• Number of hydraulic fracturing stages 

• Injected volumes 

42 ROCMECH is based on an earlier simulator called ROCMAS (Noorishad and Tsang, 1997; Rutqvist et al., 2001). The 

ROCMECH simulator employs the finite element method, includes several plastic models such as the Mohr-Coulomb and 

Drucker-Prager models, and can simulate the geomechanical behavior of multiple porosity/permeability continuum 

systems. Furthermore, ROCMECH can accurately simulate the process of hydraulic fracturing, i.e., the evolution and 

propagation of fractures in the formation following stimulation operations. 

72



• Pressure evolution during injection 

• Volumes of fracturing fluid recovered 

Uncertainty in the data will be addressed by first analyzing base cases that involve reasonable 

estimates of the various parameters and conditions and then conducting sensitivity analyses that 

cover (and extend beyond) the possible range of expected values of all relevant parameters. 


The subsurface migration modeling project is proceeding along two main tracks. The first 

addresses the geomechanical reality of the mechanisms and seeks to determine whether it is 

physically possible (as determined and constrained by the laws of physics and the operational 

quantities and limitations involved in hydraulic fracturing operations) for the six migration 

mechanisms (Scenarios A to D2) to occur. The second axis focuses on contaminant transport, 

assuming that a subsurface migration has occurred as described in the six scenarios, and attempts 

to determine a timeframe for contaminants (liquid or gas phase) escaping from a shale gas 

reservoir to reach the ground water aquifer. 

Analysis of Consequences of Geomechanical Wellbore Failure (Scenario A). A large database of 

relevant publications has been assembled, and several important well design parameters and 

hydraulic fracturing operational conditions have been identified as a foundation for the simulation. 

Two pathways for migration have been considered using TOUGH+RGasH2OCont: cement 

separation from the outer casing or a fracture pattern affecting the entire cement, from the 

producing formation to the point where the well intercepts the ground water formation. 

A separate geomechanical study using TOUGH+RealGasH2O and ROCMECH will also assess the 

feasibility of either a fracture developing in weak cement around a wellbore or a cement-wellbore 

separation during the hydraulic fracturing process. The numerical simulation of the fracture 

propagation considered fracture development in the cement near the “heel” of a horizontal well 

during stimulation immediately after creation of the first fracture using varied geomechanical 

properties of gas-bearing shales. The work also involves sensitivity analyses of factors that are 

known to be important, as well as those that appear to have secondary effects (for completeness). 

Recent activities have focused mainly on such sensitivity analyses. 

Analysis of the Consequences of Induced Fractures Reaching Ground Water Resources and after 

Intercepting Conventional Reservoirs (Scenarios B1 and B2). A high-definition geomechanical study, 

involving a complex fracture propagation model that incorporates realistic data and parameters (as 

gleaned from the literature and discussions with industry practitioners) was completed. A 

sensitivity analysis of the fracture propagation to the most important geomechanical properties 

and conditions is partially completed and will be included in the final publication. 

73



Simulations of gas and contaminant migration from the shale gas reservoir through fractures into 

ground water are also in progress. The simulation domain is subdivided up to 300,000 elements 43 

and up to 1.2 million equations, which requires very long execution times that can range from 

several days to weeks. Work continues to streamline the processing of the simulation to 

significantly reduce the execution time requirements. 

Scoping calculations are in development to provide time estimates for the migration of gas and 

dissolved contaminants from the shale gas reservoir to the drinking water resource through a 

connecting fracture. As illustrated in Figure 15, the simulated system is composed of a 100-meterthick 

aquifer (from 100 to 200 meters below the surface), a fracture extending from the bottom of 

the gas reservoir at 1,200 meters below surface to the base of the aquifer, which is 1,000 meters 

above the gas reservoir. These scoping studies indicated that the most important parameters and 

conditions were the permeability of the gas reservoir (matrix), the fracture permeability, the 

distance between the aquifer and the shale reservoir, and the pressure regimes in the aquifer and 

the shale. Results from this work are being analyzed and will be published when complete. 

Analysis of Consequences of Activation of Native Faults and Fractures (Scenario C). The simulation 

conditions for the analysis of contaminant transport through native fractures and faults in response 

to the stimulation process have been determined, and the variations used to conduct a sensitivity 

analysis are being developed. 

A geomechanical study using the TOUGH-FLAC 44 simulator began in March 2012 to investigate the 

possibility that hydraulic fracturing injections may create a pathway for transport through fault 

reactivation. The simulation input represents the conditions in the Marcellus Shale. Scoping 

calculations were developed to study the potential for injection-induced fault reactivation 

associated with shale gas hydraulic fracturing operations. From these scoping calculations, the 

LBNL simulation results suggest that the hydraulic fracturing stimulation, under conditions 

reported in published literature, does not appear to activate fault rupture lengths greater than 40 to 

50 meters and could only give rise to microseismicity (magnitude



through the shale gas reservoir into the weak/fractured cement around, or the unplugged wellbore 

of offset wells (Figures 18 and 19). The LBNL is investigating two mechanisms for fluid 

communication. In the first case, the fractures extend across the shale stratum into a nearby 

depleted conventional reservoir with abandoned defective wells in the overburden or 

underburden. The energy for the lift of contaminants in this case is most likely provided by the 

higher pressure of the fluids in the shale (as the abandoned reservoir pressure is expected to be 

low) and by buoyancy; the main contaminant reaching the ground water is expected to be gas. In 

the second case, fractures extend from a deeper over-pressurized saline aquifer through the entire 

thickness of the shale to an overburden (a depleted conventional petroleum reservoir with 

abandoned unsealed wells). The energy for the lift of contaminants in this case is most likely 

provided by the higher pressure of the fluids in the shale and in the saline aquifer in addition to 

buoyancy, and the contaminants reaching the ground water are expected to include gas and solutes 

encountered in the saline aquifer. 


The QAPP, “Analysis of Environmental Hazards Related to Hydrofracturing (Revision: 0),” was 

accepted by the EPA on December 7, 2011 (LBNL, 2011). 

A TSA of the work being performed by the LBNL was conducted on February 29, 2012. The 

designated EPA QA Manager found the methods in use satisfactory and further recommendations 

for improving the QA process were unnecessary. Work performed and scheduled to be performed 

was within the scope of the project. Work is proceeding on Scenarios A through D2 as described in 

Section 4.1.3. Reports, when presented, will be subjected to appropriate QA review. 

4.2. Surface Water Modeling 


The EPA is using established surface water transport theory and models to identify concentrations 

of selected hydraulic fracturing-relevant chemicals at public water supply intakes located 

downstream from wastewater treatment facilities that discharge treated hydraulic fracturing 

wastewater to rivers. This work is expected to provide data that will be used to answer the 

research question identified in Table 28. 

Table 28. Secondary research question addressed by modeling surface water discharges from wastewater treatment 

facilities accepting hydraulic fracturing wastewater. 





What are the potential impacts from surface water disposal of treated 

hydraulic fracturing wastewater on drinking water treatment 

facilities 


When an operator reduces the injection pressure applied to a well, the direction of fluid flow 

reverses, leading to the recovery of flowback and produced water, collectively referred to as 

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“hydraulic fracturing wastewater.” 45 The wastewater is generally stored onsite before being 

transported for treatment, recycling or disposal. Most hydraulic fracturing wastewater is disposed 

in UIC wells. In Pennsylvania, however, wastewater has been treated in wastewater treatment 

facilities (WWTFs), which subsequently discharge treated wastewater to surface water bodies. 

The extent to which common treatment technologies used in WWTFs effectively remove chemicals 

found in hydraulic fracturing wastewater is currently unclear. 46 Depending in part on the 

concentration of chemicals in the effluent, drinking water quality and the treatment processes at 

public water systems (PWSs) downstream from WWTFs might be negatively affected. For example, 

bromide in source waters can cause elevated concentrations of brominated disinfection byproducts 

(DBPs) in treated drinking water (Brown et al., 2011; Plewa et al., 2008), 47 which are regulated by 

the National Primary Drinking Water Regulations. 48 To learn more about impacts to downstream 

PWSs, the Pennsylvania Department of the Environment asked 25 WWTFs that accept Marcellus 

wastewater to monitor effluent for parameters such as radionuclides, total dissolved solids (TDS), 

alkalinity, chloride, sulfate, bromide, gross alpha, radium-226 and -228, and uranium in March 2011 

(PADEP, 2011). The department also asked 14 PWSs with surface water intakes downstream from 

WWTFs that accept Marcellus wastewater to test for radionuclides, TDS, pH, alkalinity, chloride, 

sulfate, and bromide (PADEP, 2011). Bromide and radionuclides are of particular concern in 

discharges because of their carcinogenicity and reproductive and developmental affects. 

The EPA will use computer models—mass balance, empirical, and numerical—to estimate generic 

impacts of bromide and radium in wastewater discharges, based on the presence of these chemicals 

in discharge data from WWTFs in Pennsylvania, impacts to downstream PWSs’ ability to meet 

National Primary Drinking Water Regulations for DBPs and radionuclides, and the potential human 

health impacts from the chemicals. 49 Uranium, also a radionuclide, was frequently not detected by 

analytical methods for the discharges and therefore not considered for simulations. The generic 

model results are designed to illustrate the general conditions under which discharges might cause 

impacts on downstream public water supplies. The analysis will include the effect of distance to the 

PWS, discharge concentration, and flow rate in the stream or river, among others. The uncertainties 

in these quantities will be addressed through Monte Carlo analysis, as described below. 

A steady-state mass balance model provides an upper-bound impact assessment of the transport 

simulation and a partially transient approach simulates the temporal variation of effluent 

concentration and discharge. Key data collected to model the transport of potential contaminants 

include actual effluent data from WWTF discharges and receiving water body flow rates. Effluent 

data can be obtained from National Pollutant Discharge Elimination System (NPDES) monitoring 

45 Produced water is produced from many oil and gas wells and not unique to hydraulic fracturing. 

46 See Section 5.2 for a more thorough discussion and for EPA-funded research into this question. 

47 See Section 5.3 for more information on DBPs and related research. 

48 Authorized by the Safe Drinking Water Act. 

49 Discharge data for four WWTFs in Pennsylvania that accepted oil and gas wastewater during 2011 are available on the 

EPA’s website at http://www.epa.gov/region3/marcellus_shale/. 

76



data reported to states by the dischargers. 50 NPDES information also documents the design of the 

industrial treatment plants, which can give insights into the capabilities of these and similarly 

designed treatment plants. The US Geological Survey (USGS) provides limited water quality and 

flow rate data from monitoring stations within the watersheds of the receiving water bodies. The 

surface water modeling results will directly address the applicable secondary research question 

(Table 28) by evaluating the possible impacts from a permitted release of treated effluent on both a 

downstream drinking water intake and in a watershed where there may be multiple sources and 

receptors. 51 


Multiple approaches generate results on impacts: steady-state mass balance; transient empirical 

modeling; and a transient, hybrid empirical-numerical model developed by the EPA. The results of 

the mass balance model simulate possible impacts during a large volume, high concentration 

discharge without natural attenuation of contaminants. The empirical model and a hybrid 

empirical-numerical model estimate impacts in a more realistic setting with variable chemical 

concentrations, discharge volumes, and flow rates of the receiving surface water. The numerical 

model confirms the results of the empirical and hybrid models. The numerical modeling is based on 

an approach developed for this study from existing methods (Hairer et al., 1991; Leonard, 2002; 

Schiesser, 1991; Wallis, 2007). Application of these three types of models provides a panoramic 

view of possible impacts and enhances confidence in the study results. 

Mass Balance Approach Estimates Impacts from an Upper-Bound Discharge Scenario. A simple, 

steady-state mass balance model simulates drinking water impacts from upper-bound discharge 

cases. This model assumes that the total mass of the chemical of interest is conserved during 

surface water transport and that the chemical concentration does not decrease due to reaction, 

decay, or uptake. The model estimates potential impacts to downstream PWSs using the maximum 

effluent concentration, maximum WWTF discharge volume, minimum flow rate in the receiving 

stream, and the distance to the downstream PWS intake. The EPA constructed generic discharge 

scenarios for rivers with varying flow regimes to determine the potential for adverse impacts at 

drinking water intakes. Because the parameters describing transport are uncertain, Monte Carlo 

techniques will be used to generate probabilistic outputs of the model. 

Empirical Model Estimates Impacts with Varying Discharge Volumes over Time. The upper-bound 

case simulated in the steady-state mass balance model may be too conservative (by providing 

larger concentration estimates) to accurately represent downstream concentrations of chemicals 

since effluent concentrations, treatment plant discharge volumes, and flow rates change over time. 

Therefore, the EPA will also use an empirical transport model originally developed by the USGS 

(Jobson, 1996) to simulate impacts from varying monthly discharge volumes over time. The 

50 Information on WWTF discharges in Pennsylvania can be found at https://www.paoilandgasreporting.state.pa.us/ 

publicreports/Modules/Welcome/Welcome.aspx. 

51 Impacted watersheds may also have other sources of compounds of interest, possibly acid mine drainage and coal-fired 

utility boilers. This is discussed in more detail in Section 5.1, which also outlines work being done by the EPA to assess the 

contribution of hydraulic fracturing wastewater to contamination in surface water bodies. 

77



empirical approach is based on tracer studies performed around the United States since the early 

1970s (e.g., Nordin and Sabol (1974)). The empirical equations address two major difficulties in 

applying models to chemical transport scenarios: the inability to estimate travel times from crosssectional 

data and the reduction of concentration due to turbulent diffusion. The empirical equation 

approach gives an estimate of travel time and peak concentration so that the model does not need 

to be calibrated to tracer data. 

Hybrid Empirical-Numerical Model Estimates Impacts for River Networks. The original empirical 

approach was suited for a single river segment, or reach, of spatially uniform properties. The hybrid 

empirical-numerical model being developed by the EPA to expand the capabilities of the justdescribed 

Jobson technique will easily account for multiple reaches that can form branching river 

networks. Similar to all statistical relationships, the empirical equations do not always match tracer 

data exactly; therefore, the EPA is including the ability to perform Monte Carlo techniques in the 

software being developed. The EPA will confirm the accuracy of the hybrid model with tracer data 

that fall within the range of Jobson’s original set of inputs (taken from Nordin and Sabol (1974)) as 

well as later data from the Yellowstone River that provide a real-world test of this approach 

(McCarthy, 2009). 

The numerical portion of the hybrid model provides a direct and automatic comparison with the 

empirical equations. The method is based on a finite difference solution to the transport equation 

using recent developments in modeling to improve accuracy (Hairer et al., 1991; Leonard, 2002; 

Schiesser, 1991; Wallis, 2007). By including this numerical method, a hybrid empirical-numerical 

approach can be achieved. The empirical travel times from Jobson (1996) can be used to 

parameterize velocity in the numerical method. Dispersion coefficients can be derived from 

empirical data or a method developed by Deng et al. (2002). Using these approaches provides 

improved accuracy in the simulation results. The EPA will prepare a user’s guide to the model and 

make both the computer model and user’s guide widely available for duplicating the results 

prepared for this project and for more general use. 

For the generic simulations described above, effluent concentrations and discharge volumes will be 

modeled directly as variable inputs based on the effluent data evaluation (as discussed next in 

Section 4.2.4), while flow conditions will be modeled as low, medium, and high flow. Because the 

parameters describing transport are uncertain, statistical measures and Monte Carlo techniques 

will be used to generate probabilistic outputs from the model. To provide further assurance of the 

accuracy of the EPA hybrid model results, the Water Quality Simulation Package has been used to 

simulate tracer data and confirm the results (Ambrose et al., 1983; Ambrose and Wool, 2009; 

DiToro et al., 1981). 


The models described above are being used to determine potential impacts of treated wastewater 

discharges on downstream PWSs. Enough data have been identified to perform generic simulations 

for the steady-state mass balance simulations and hybrid empirical-numerical models with variable 

effluent concentration and plant discharge. For two WWTFs in Pennsylvania, USGS flow data have 

been compiled for segments of the rivers that reach downstream to drinking water intakes (50 to 

100 miles downstream) for the two locations. These data will be used to generate realistic model 

78



inputs to assess, in a generic sense, the potential impacts of discharges from realistic treatment 

plants. 

The EPA-developed hybrid empirical-numerical model has been favorably compared against a 

tracer experiment used by Jobson (1996) in developing the original empirical formulas. Calibration 

or other parameter adjustment was unnecessary for the hybrid model to produce accurate results. 

The EPA plans to compare the hybrid model to five more of the tracer experiments to cover the 

range of flow conditions used by Jobson (1996). Additionally, data from the more recent 

Yellowstone River experiment (McCarthy, 2009) are being prepared for testing the hybrid model. 

Similar comparisons of empirical to tracer experiments were performed by Reed and Stuckey 

(2002) for streams in the Susquehanna River Basin. The EPA Water Quality Simulation Package 

numerical model was set up to simulate the same tracer experiment performed for the hybrid 

model. Additional calibration is planned to refine the results from the Water Quality Simulation 

Package. After completing the evaluation of the hybrid model, the WWTF simulations will be 

completed. 


A description of the EPA-developed empirical-numerical model and application of the empiricalnumerical 

and mass balance models to tracer experiments is being developed by EPA scientists and 

are expected to be submitted for publication in a peer-reviewed journal. The results from testing of 

the models and the analysis of the WWTF effluent data will be included in another peer-reviewed 

journal article. 


The initial QAPP for “Surface Water Transport of Hydraulic Fracturing-Derived Waste Water” was 

approved by the designated EPA QA Manager on September 8, 2011 (US EPA, 2012s). The QAPP 

was subsequently revised and approved on February 22, 2012. 

A TSA was conducted on March 1, 2012. The designated EPA QA Manager found the methods in use 

satisfactory and further recommendations for improving the QA process were unnecessary. An 

audit of data quality (ADQ) will be performed to verify that the quality requirements specified in 

the approved QAPP were met. 

79



4.3. Water Availability Modeling 

The EPA selected humid and semi-arid river basins as study areas for identifying potential impacts 

to drinking water resources from large volume water withdrawals (1 to 9 million gallons per well 

for the selected river basins) associated with hydraulic fracturing operations. This work is expected 

to address the research questions listed in Table 29. 

Table 29. Research questions addressed by modeling water withdrawals and availability in selected river basins. 




• How much water is used in hydraulic fracturing operations, and 

what are the sources of this water 

• How might water withdrawals affect short- and long-term water 

availability in an area with hydraulic fracturing 

• What are the possible impacts of water withdrawals for 

hydraulic fracturing operations on local water quality 


The volume of water needed in the hydraulic fracturing process for stimulation of unconventional 

oil and gas wells depends on the type of formation (e.g., coalbed, shale, or tight sands), the well 

construction (e.g., depth, length, vertical or directional drilling), and fracturing operations (e.g., 

fracturing fluid properties and fracture job design). Water requirements for hydraulic fracturing of 

CBM range from 50,000 to 250,000 gallons per well (Holditch, 1993; Jeu et al., 1988; Palmer et al., 

1991; Palmer et al., 1993), although much larger volumes of water are produced during the lifetime 

of a well in order to lower the water table and expose the coal seam (ALL Consulting, 2003; S.S. 

Papadopulos & Associates Inc., 2007a, b). The water usage for hydraulic fracturing in shale gas 

plays is significantly larger than CBM reservoirs—2 to 4 million gallons of water are typically 

needed per well (API, 2010; GWPC and ALL Consulting, 2009; Satterfield et al., 2008). The volume 

of water needed for well drilling is understood to be much less, from 60,000 gallons in the 

Fayetteville Shale to 1 million gallons in the Haynesville Shale (GWPC and ALL Consulting, 2009). 

Water-based mud systems used for drilling vertical or horizontal wells generally require that fresh 

water (non-potable, potable, or treated) be used as makeup fluid, although wells can also be drilled 

using compressed air and oil-based fluids. 

Water needed for hydraulic fracturing may come from multiple sources with varying quality. 

Sources may include raw surface and ground water, treated water from public water supplies, and 

water recycled from other purposes such as flowback and produced water from previous oil and 

gas operations or even acid mine drainage. The quality of water needed is dependent on the other 

chemicals in the fracturing fluid formulations, availability of water source, and the chemical and 

physical properties of the formation. The goal of this project is to investigate the water needs and 

sources to support hydraulic fracturing operations at the river basin and county spatial scales and 

to place this demand in the watershed context in terms of annual, seasonal, and monthly water 

availability. 

The EPA recognizes the unique circumstances of the geography and geology of every 

unconventional oil and gas resource and has chosen two study sites to initially explore and identify 

80



the potential differences related to water acquisition. The study areas includes two river basins: the 

Susquehanna River Basin (SRB), located in the eastern United States (humid climate) and overlying 

the Marcellus Shale gas reservoir (Figure 20), and the Upper Colorado River Basin (UCRB), located 

in the western United States (semi-arid climate) and overlying the Piceance structural basin and 

tight gas reservoir (Figure 21). The EPA is calibrating and testing watershed models for the study; 

the SRB and UCRB watershed models were previously calibrated and tested in the EPA 

investigation of future climate change impacts on watershed hydrology (the “20 watersheds study”) 

(Johnson et al., 2011). 

Figure 20. The Susquehanna River Basin, overlying a portion of the Marcellus Shale, is one of two study areas 

chosen for water availability modeling. Water acquisition for hydraulic fracturing will focus on Bradford and 

Susquehanna Counties in Pennsylvania. (GIS data obtained from ESRI, 2010a; US EIA, 2011e; US EPA, 2007.) 

81



Figure 21. The Upper Colorado River Basin, overlying a portion of the Piceance Basin, is one of two river basins 

chosen for water availability modeling. Water acquisition for hydraulic fracturing will focus on Garfield and Mesa 

Counties in Colorado. (GIS data obtained from ESRI, 2010a; US EIA, 2011e; US EPA, 2007.) 

In both study areas, the river watershed and its subsurface basin include the river flows and 

reservoir and aquifer storages based on the hydrologic cycle, geography, geology, and water uses. 

The EPA’s goal is to explore future hypothetical scenarios of hydraulic fracturing use in the eastern 

and western study areas based on current understanding of hydraulic fracturing water acquisition 

and watershed hydrology. The EPA intends to characterize the significance, or insignificance, of 

hydraulic fracturing water use on future drinking water resources for the two study areas. The 

research will involve detailed representation of water acquisition supporting hydraulic fracturing 

in the Bradford County and Susquehanna County area in Pennsylvania and in the Garfield County 

and Mesa County areas of Colorado. These areas have concentrated hydraulic fracturing activity, as 

discussed below. 

4.3.1.1. Susquehanna River Basin 

Geography, Hydrology, and Climate. The SRB has over 32,000 miles of waterways, drains 27,510 

square miles, and covers half of Pennsylvania and portions of New York and Maryland (Figure 20) 

(SRBC, 2006). On average, the SRB contributes 18 million gallons of water every minute (25,920 

million gallons per day, or MGD) to the Chesapeake Bay (SRBC, 2006). The humid climate of the 

region experiences long-term average precipitation of 37 to 43 inches per year (McGonigal, 2005). 

82



Oil and Gas Resources and Activity. Large portions of the SRB watershed are underlain by the 

Marcellus Shale formation, which is rich in natural gas. Estimates of recoverable and undiscovered 

natural gas from this formation range from 42 to 144 trillion cubic feet (Coleman et al., 2011) and 

production well development estimates for the next two decades range as high as 60,000 total wells 

drilled by 2030 (Johnson et al., 2010). The Pennsylvania Department of Environmental Protection 

reports that the number of drilled wells in the Marcellus Shale has been increasing rapidly. In 2007, 

only 27 Marcellus Shale wells were drilled in the state; in 2010 the number of wells drilled was 

1,386. Data extracted from FracFocus 52 indicate that the total vertical depth of wells in Bradford 

and Susquehanna Counties is between 5,000 and 8,500 feet (mean of 6,360 feet) below ground 

surface, which implies that this depth range is the target production zone for the Marcellus Shale. 

Water Use. The SRB supports a population of over 4.2 million people. Table 30 lists the estimated 

water use for the SRB and Bradford and Susquehanna Counties. The Susquehanna River Basin 

Commission estimates consumptive water use in five major categories, with PWSs consuming the 

greatest volume of water per day (325 MGD) followed by thermoelectric energy production (190 

MGD) (Richenderfer, 2011). The greatest water withdrawals per day in Bradford and Susquehanna 

Counties are for drinking water (8.25 MGD for combined public and domestic use) and self-supplied 

industrial uses (4.59 MGD). 

Table 30. Water withdrawals for use in the Susquehanna River Basin (Richenderfer, 2011) and Bradford and 

Susquehanna Counties, Pennsylvania (Kenny et al., 2009). 

Use 

Public supply 

Self-supplied domestic 

Irrigation (crop) 

Irrigation (golf courses) 

Self-supplied industrial 

Livestock 

Thermoelectric 

Mining 

Other 

Water Withdrawals (million gallons per day) 

Susquehanna River Basin 

Not reported 

Bradford and Susquehanna 

Counties, Pennsylvania 

325 4.59 

Not reported 3.66 

Not reported 

22.0 

Not reported 

190 

(energy production, non-gas) 

10.0 

50.0 

(recreation) 

0.110 

0.060 

4.59 

3.41 

0.00 

0.10 

Not reported 

Figure 22 displays the geographic distribution of PWSs in the SRB. 53 

52 See Section 3.5 for additional information on the FracFocus data extraction and analysis research project. 

53 The location and type of drinking water supply is significant when represented in watershed hydrology models. The 

extraction of surface water is removed from the watershed model subbasin from its main river reach. The extraction of 

ground water is removed from the model subbasin from its ground water storage. 

83



Figure 22. Public water systems in the Susquehanna River Basin (US EPA, 2011j). The legend symbol size for public 

water systems is proportional to the number of people served by the systems. For example, the smallest circle 

represents water systems serving 25 to 100 people and the largest circle represents systems serving over 100,000 

people. 

The Susquehanna River Basin Commission reports that the oil and gas industry consumed over 1.6 

billion gallons of water for well drilling and hydraulic fracturing in the entire SRB from July 1, 2008, 

to February 14, 2011. If averaged over the entire time, this is roughly 1.7 MGD. This amount of 

water was used for approximately 1,800 gas production wells with about 550 wells hydraulically 

fractured by the end of 2010 (Richenderfer, 2011). The majority (65%) of the water came from 

direct surface water withdrawals, with smaller fractions from PWSs (35%) and ground water (very 

small). The average total volume of fluid used per well was 4.2 million gallons, with about 10% of 

the volume as treated flowback and 90% fresh water (Richenderfer, 2011). The average recovery of 

fluids was reported to be 8% to 12% of the injected volume within the first 30 days (Richenderfer, 

2011). 

84



Water use reported in FracFocus for Bradford and Susquehanna Counties ranges between 2 and 9 

million gallons per well (median of 4.7 million gallons per well; (GWPC, 2012a)), consistent with 

data reported by the Susquehanna River Basin Commission. 54 In this part of the SRB, the wells are 

almost exclusively horizontal and producing from the Marcellus Shale. The operators are blending 

treated produced water into hydraulic fracturing fluids (Rossenfoss, 2011). 

4.3.1.2. Upper Colorado River Basin 

Geography, Hydrology, and Climate. The UCRB drains an area of 17,800 square miles and is 

characterized by high mountains in the east and plateaus and valleys in the west. The average 

discharge of the Colorado River near the Colorado-Utah state line is about 2.8 million gallons per 

minute (about 4,000 MGD) (Coleman et al., 2011). Precipitation ranges from 40 inches per year or 

more in the eastern part of the basin to less than 10 inches per year in the western part of the basin 

(Spahr et al., 2000). 

Oil and Gas Resources and Activity. The UCRB has a long history of oil, gas, and coal exploration. The 

Piceance Basin is a source of unconventional natural gas and oil shale. The basin was originally 

exploited for its coal resources, and the associated CBM production peaked around 1992 (S.S. 

Papadopulos & Associates Inc., 2007a). The Upper Cretaceous Williams Fork Formation, a thick 

section of shale, sandstone, and coal, has been recognized as a significant source of gas since 2004 

(Kuuskraa and Ammer, 2004). The wells producing gas from the Williams Fork are either vertically 

or directionally (“S”-shaped wells) drilled rather than horizontal. While the deeper Mancos Shale is 

considered a major resource for shale gas (Brathwaite, 2009), it must be exploited with horizontal 

drilling methods, and the economics are such that only prospecting wells are being drilled at this 

time (personal communication, Jonathan Shireman, Shaw Environmental & Infrastructure, May 1, 

2012). Estimated reserves in coalbeds and unconventional tight gas reservoirs are nearly 84 trillion 

cubic feet (Tyler and McMurry, 1995). 

Gas production activities occur in the following counties within the UCRB: Delta, Eagle, Garfield, 

Grand, Gunnison, Hinsdale, Mesa, Montrose, Ouray, Pitkin, Routt, Saguache, and Summit (COGCC, 

2012b). Table 31 indicates that the greatest drilling activity has been in Garfield and Mesa Counties 

(Figure 21), where well completions increased steadily from 2000 (212 wells) to 2008 (2,725 

wells), then dropped slightly to 1,160 wells in 2010 (COGCC, 2012b). The total vertical depth of 

wells in Garfield County and Mesa County as reported in FracFocus implies that the location of the 

target production zone(s) lies between 6,000 and 13,000 feet (mean of 8,000 feet) below ground 

surface. 

54 More information on FracFocus is available in Section 3.5. 

85



Table 31. Well completions for select counties in Colorado within the Upper Colorado River Basin watershed 

(COGCC, 2012b). 

County 

2000 

2001 

Annual Well Completions from 2000 to 2010 

2002 2003 2004 2005 2006 2007 2008 

2009 

2010 

Delta 

8 5 8 3 2 

4 

Garfield 

Gunnison 

207 

244 

287 507 679 892 1269 1689 2255 

2 3 2 1 11 8 2 

1050 

4 

1139 

2 

Mesa 

5 

21 

26 18 53 203 336 501 470 

43 

21 

Montrose 

4 

2 2 3 4 

1 

Routt 

10 

21 

8 5 2 

4 

1 

Water Use. The UCRB supports a population of over 275,000 people. Table 32 lists the estimated 

water use for the UCRB and Garfield and Mesa Counties in Colorado. According to the USGS, the 

total water use in 2005 in the UCRB and Garfield and Mesa Counties was dominated by irrigation 

(1702 and 1200 MGD, respectively), followed by public and domestic water supply (60.4 and 29.6 

MGD), and thermoelectric energy production (44 MGD) (Ivahnenko and Flynn, 2010; Kenny et al., 

2009). 

Table 32. Water withdrawals for use in the Upper Colorado River Basin (Ivahnenko and Flynn, 2010) and Garfield 

and Mesa Counties in Colorado (Kenny et al., 2009). 

Use 

Water Withdrawals (million gallons per day) 

Upper Colorado River Basin 

Garfield and Mesa Counties, Colorado 

Public supply 58.6 29.2 

Self-supplied domestic 1.81 1.35 

Irrigation (crop) 1702 1200 

Irrigation (golf courses) 8.00 3.50 

Self-supplied industrial 2.71 1.05 

Livestock 0.870 0.840 

Thermoelectric 

43.9 

(non-consumptive) 

43.9 

(non-consumptive) 

Mining 0.390 0.280 

Other 

Not reported 

1.88 

(aquaculture) 

Figure 23 displays the distribution of public water systems in the basin. Interbasin water transfers, 

mining, urbanization, and agriculture are the principal human activities that potentially impact 

water quantity in the UCRB. 

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Figure 23. Public water systems in the Upper Colorado River Basin (US EPA, 2011j). The legend symbol size for 

public water systems is proportional to the number of people served by the systems. For example, the smallest circle 

represents water systems serving 25 to 100 people and the largest circle represents systems serving over 70,000 

people. 

The State of Colorado estimates that total annual statewide water demand for hydraulic fracturing 

associated with oil and gas wells increased from 4.5 billion gallons in 2010 to almost 4.9 billion 

gallons in 2011 (12.3 MGD in 2010 to almost 13.4 MGD in 2011), which parallels the increasing 

number of wells spudded, as shown in Table 33 (COGCC, 2012a). The amount of water demand was 

determined using the number of wells spudded (horizontal and vertical) multiplied by an average 

amount of water required for hydraulic fracturing per well type based on data reported in 2011. 

COGCC (2012a) estimates the average water use per well at about 1.6 million gallons in 2010 and 

2011. 

87



Table 33. Estimated total annual water demand for oil and gas wells in Colorado that were hydraulically fractured in 

2010 and 2011 (COGCC, 2012a). Data for vertical and horizontal wells are not differentiated in the estimates and well 

spud dates. 

Category 

Year 

2010 2011 

Wells spudded 2,753 2,975 

Estimated annual water demand 

(million gallons) 

Estimated water use per well 

(million gallons) 

4,531 4,857 

1.65 1.63 

Data extracted from FracFocus for Garfield and Mesa Counties shows water use per well between 1 

and 9 million gallons (median 1.3 million gallons), which is consistent with the Colorado Oil and Gas 

Compact Commission data (COGCC, 2012a; GWPC, 2012a). In this part of the Piceance Basin (Figure 

21), the majority of wells are vertically drilled and producing gas from the Williams Fork tight 

sandstones. Based on conversations with Berry Petroleum, Williams Production, Encana Oil and 

Gas, and the Colorado Field Office of the US Bureau of Land Management, the water used to fracture 

wells in this area is entirely recycled formation water that is recovered during production 

operations. Fresh water is used only for drilling mud, cementing the well casing, hydrostatic testing, 

and dust abatement and is estimated to be about 251,000 gallons per well (US FWS, 2008). 


Watershed Models. In order to assess the impact of hydraulic fracturing water withdrawals on 

drinking water availability at watershed and county spatial scales as well as annual, seasonal, 

monthly, and daily time scales, the EPA is developing separate hydrologic watershed models for the 

SRB and UCRB. The models are based in part on the calibrated and verified watershed models 

(hereafter called the “foundation” models) of the EPA Global Change Research Program (Johnson et 

al., 2011), namely the Hydrologic Simulation Program FORTRAN (HSPF) 55 and the Soil and Water 

Assessment Tool (SWAT). 56 Both HSPF and SWAT are physically based, semi-distributed watershed 

models that compute changes in water storage and fluxes within drainage areas and water bodies 

over time. Each model can simulate the effect of water withdrawals or flow regulation on modeled 

stream or river flows. Key inputs for the models include meteorological data, land use data, and 

time series data representing water withdrawals. The models give comparable performance at the 

scale of investigation (Johnson et al., 2011). 

Modeling of the SRB will be completed using the calibrated and tested HSPF. Since its initial 

development nearly 20 years ago, HSPF has been applied around the world; it is jointly sponsored 

by the EPA and the USGS, and has extensive documentation and references (Donigian Jr., 2005; 

Donigian Jr. et al., 2011). The choice of HSPF in the SRB, a subwatershed within the larger 

55 More information on the HSPF model including self-executable file, is available at http://www.epa.gov/ceampubl/ 

swater/hspf/. 

56 More information on the SWAT model including self-executable file, is available at http://swat.tamu.edu/ 

software/swat-model/. 

88



Chesapeake Bay watershed, allows benchmarking to the peer-reviewed and community-accepted 

Chesapeake Bay Program watershed model. 57 

Modeling of the UCRB will be completed using the calibrated and tested SWAT. The SWAT is a 

continuation of over 30 years of modeling efforts conducted by the US Department of Agriculture’s 

Agricultural Research Service and has extensive peer review (Gassman et al., 2007). SWAT is an 

appropriate choice in the less data-rich UCRB, where hydrological response units can be 

parameterized based on publicly available GIS maps of land use, topography, and soils. 

The SRB and UCRB models will build on the “foundation” models and be updated to represent 

baseline and current watershed conditions. The baseline model will add reservoirs and major 

consumptive water uses for watershed conditions of the year 2000 for the SRB and 2005 for the 

UCRB. The baseline year predates the significant expansion of hydraulic fracturing in the basin 

(2007 for SRB, 2008 for UCRB) and corresponds with the USGS’ water use reports (every five years 

since 1950) and the National Land Cover Dataset (Homer et al., 2007). The baseline models will 

represent the USGS’s major water use categories, including the consumptive component of both 

PWS and domestic water use, and the other major water use categories (irrigation, livestock, 

industrial, mining, thermoelectric power). The snapshot of each watershed in the year 2010 will be 

the current model representation in both basins. The current models will include all water use 

categories from the baseline model plus hydraulic fracturing water withdrawals and refine the 

representation of PWS and hydraulic fracturing in county-scale focus areas—Garfield/Mesa 

Counties in Colorado and Bradford/Susquehanna Counties in Pennsylvania. 

The foundation, baseline, and current watershed models will be exposed to the historical 

meteorology (precipitation, temperature) from National Weather Service gauges located within 

each watershed. The calibration and validation of the foundation, baseline, and current models will 

be checked by comparing goodness-of-fit statistics and through expert judgment of comparisons of 

observed and modeled stream discharges. 

Key characteristics of model configuration include: 

• Land use will be based on the 2001 National Land Cover Dataset (Homer et al., 2007). 

Land use data are used for segmenting the basin land area into multiple hydrologic 

response units, each with unique rainfall/runoff response properties. For the SWAT 

model, soil and slope data will also be used for defining unique hydrologic response units. 

• Each basin will be segmented into multiple subwatersheds at the 10-digit hydrologic unit 

scale. 58 

57 More information on the Chesapeake Bay Program watershed model is available at http://www.chesapeakebay.net/ 

about/programs/modeling/53/. 

58 Hydrologic units refer to the Watershed Boundary Dataset developed through a coordinated effort by the USGS, the US 

Department of Agriculture, and the EPA. The intent of defining hydrologic units for the Watershed Boundary Dataset is to 

establish a baseline drainage boundary framework, accounting for all land and surface areas. Several levels of watershed 

are defined based on size. A 10-digit hydrologic unit is a level 5 watershed of average size 227 square miles (USDA, 2012). 

89



• Observed meteorological data for water years 1972 to 2004 for SRB and 1973 to 2003 for 

UCRB will be applied to assess water availability over a range of weather conditions. 

• The effect of reservoirs on downstream flows will be simulated using reservoir 

dimensions/operation data from circa 2000 from the Chesapeake Bay Program watershed 

model (Phase 5.3; (US EPA, 2010a)). 

• Point source dischargers with NPDES-permitted flow rates of at least 1 MGD will be 

represented as sources of water on the appropriate stream reaches. 

• Surface water withdrawals will be simulated for three unique water use categories: 

hydraulic fracturing water use, PWSs, and other. For the “other” category, the magnitude 

of withdrawals from modeled stream reaches will be based on water use estimates 

developed by the USGS (year 2000 for SRB; year 2005 for UCRB). 59 

Modeling Future Scenarios. The modeling effort will also simulate a snapshot of heightened annual 

hydraulic fracturing relative to the baseline and current condition models at levels that could 

feasibly occur over the next 30 years, based on recent drilling trends and future projections of 

natural gas production (US EIA, 2012; US EPA, 2012w). Because projections of future conditions are 

inherently uncertain, three separate scenarios will be simulated: business-as-usual, energy plus, 

and green technology. The scenarios assume distinct levels of natural gas drilling and hydraulic 

fracturing freshwater use and, therefore, apply distinct hydraulic fracturing water withdrawal time 

series to modeled stream reaches. Further, significant population growth is projected in 

Garfield/Mesa Counties, Colorado, over the next 30 years (US EPA, 2010c), where natural gas 

extraction in the UCRB has recently been concentrated. Therefore, the UCRB future scenarios also 

consider a potential increase in PWS surface withdrawals in the basin. The balance between surface 

water availability and demand depicted in each scenario’s annual snapshot of water use will be 

assessed across a range of weather conditions (i.e., drought, dry, wet, and very wet years based on 

the historical record). A description of each scenario, and the methods used for scenario 

development, are provided below and in Tables 34 and 35. 

59 The USGS water use estimates can be found at http://water.usgs.gov/watuse/. 

90



Table 34. Data and assumptions for future watershed availability and use scenarios modeled for the Susquehanna 

River Basin. Current practices for water acquisition and disposal are tracked by the Susquehanna River Basin 

Commission (SRBC). 

Model Assumptions 

Hydraulic fracturing 

well deployment 


water management 

practices 

* US EPA, 2012w; USGS, 2011c 

† 

SRBC, 2012 

Business as Usual 

Current well inventory 

and future deployment 

schedules and playlevel 

development 

projections* 

Current practices for 

water acquisition, 

production and disposal 

tracked by SRBC † 

Future Scenarios 

Energy Plus 

Maximum projected 

development of gas 

reserves* 

Current practices for 

water acquisition, 

production and disposal 

tracked by SRBC † 

Green Technology 


and future deployment 


development 

projections* 

Increased recycling of 

produced water for 

hydraulic fracturing † 

Table 35. Data and assumptions for future watershed availability and use scenarios modeled for the Upper Colorado 

River Basin. 

Model Assumptions 

Future Scenarios 

Business as Usual Energy Plus* 


and future deployment Maximum projected 



development reserves † 


well deployment 

projections † 

Current practices for Current practices for 


water acquisition, water acquisition, 

water management 

production and disposal production and disposal 

practices 

estimated for UCRB § estimated for UCRB § 

* Reflects 2040 population increase (US EPA, 2010c) and corresponding change in PWS demand. 

† 

US EIA, 2011b, 2012; US EPA, 2012w; USGS, 2003 

§ 

US FWS, 2008 

Green Technology* 

Maximum projected 


reserves † 

Increased recycling of 

produced water for 

drilling § 

Future drilling patterns in the SRB and UCRB are assessed from National Energy Modeling System 

(NEMS) regional projections of the number of wells drilled annually from 2011to 2040 in shale gas 

(SRB) and tight gas (UCRB) plays (US EIA, 2012; US EPA, 2012w). Based on analysis of NEMS well 

projections and undiscovered resources in the Marcellus Shale (Coleman et al., 2011), peak annual 

drilling in the SRB could exceed the recent high in 2011 by as much as 50%. In the UCRB, analysis of 

NEMS well projections and undiscovered tight gas resources in the Piceance Basin (USGS, 2003) 

suggest that the 2008 peak level of drilling in the basin could be repeated in the late 2030s, when a 

growing population would exert a higher demand for freshwater. The future scenarios will 

incorporate these projections, with high-end estimates of the number of wells drilled/fractured 

applied in the energy plus scenario. 

The volume of surface water required for drilling and hydraulic fracturing varies according to local 

geology, well characteristics, and the amount of recycled water available for injection. In the SRB, 

2008 to 2011 water use data (SRBC, 2012) show that, on average, 13% of total water injected for 

91



hydraulic fracturing is composed of recycled produced water or wastewater. Per well surface water 

use in the SRB business as usual and energy plus scenarios will therefore be established as 87% of 

the 4 million gallons of water used for hydraulic fracturing, or 3.5 million gallons. The SRB green 

technology scenario reflects a condition of increased water recycling, where the 90 th percentile of 

current recycled water amount (29%) becomes the average. Per well surface water use in the SRB 

green technology scenario will therefore be established as 71% of the 4 million gallons of water 

used for hydraulic fracturing, or 2.8 million gallons. 

In the UCRB, 100% recycled water use is typical for hydraulic fracturing of tight sandstones 

(personal communication, Jonathan Shireman, Shaw Environmental & Infrastructure, May 7, 2012). 

Surface water is acquired for well drilling and cementing (0.18 million gallons), dust abatement 

(0.03 million gallons), and hydrostatic testing (0.04 million gallons) only (US FWS, 2008). Per well 

surface water use in the UCRB business as usual and energy plus scenarios will therefore be 0.25 

million gallons. For the UCRB green technology scenario, surface water will be assumed to be 

acquired for well drilling and cementing only (0.18 million gallons per well). 

Following the development of water withdrawal datasets for each scenario, model output will be 

reviewed to assess the impacts of water acquisition for hydraulic fracturing on drinking water 

supplies by evaluating annual and long-term streamflow and water demand, and identifying shortterm 

periods (daily to monthly) in which water demand exceeds streamflow. Since many public 

water supplies originate from ground water sources, simulated ground water recharge will also be 

computed. Results will be compared among the three scenarios to identify noteworthy differences 

and their implications for future management of hydraulic fracturing-related water withdrawals. 


Existing water use information for hydraulic fracturing has been collected from the Susquehanna 

River Basin Commission and the Colorado Oil and Gas Compact Commission by Shaw 

Environmental Technologies. The data underwent a QA review before submission to the modeling 

teams of The Cadmus Group, Inc. The models are being calibrated and validated. The future 

scenarios are being designed, with model simulations to follow. Work is underway and will be 

published in peer-reviewed journals when completed. 


The QAPP, “Modeling the Impact of Hydraulic Fracturing on Water Resources Based on Water 

Acquisition Scenarios (Version 1.0),” contracted through The Cadmus Group, Inc., was accepted on 

February 8, 2012 (Cadmus Group Inc., 2012a). A technical directive/contract modification dated 

April 25, 2012, modifies the scope of the project but not the procedures. Additionally, there is a 

pending QAPP revision that adapts the scope to the contract modification. 

A TSA of The Cadmus Group, Inc., contract was performed by the designated EPA QA Manager on 

June 14, 2012. The methods in use were found to be satisfactory and further recommendations for 

improving the QA process were unnecessary. Work performed and scheduled to be performed was 

within the scope of the project. 

92



The interim progress report “Development and Evaluation of Baseline and Current Conditions for 

the Susquehanna River Basin,” received on June 19, 2012, was found to be concise but detailed 

enough to meet the QA requirements, as expressed in the QAPP, its revision, and the contract 

modification/technical directive. The same was true for the interim progress report “Impact of 

Water Use and Hydro-Fracking on the Hydrology of the Upper Colorado River Basin,” submitted on 

July 2, 2012. 

93



5. Laboratory Studies 

The laboratory studies are targeted research projects designed to improve understanding of the 

ultimate fate and transport of selected chemicals, which may be components of hydraulic fracturing 

fluids or naturally occurring substances released from the subsurface during hydraulic fracturing. 

This chapter includes progress reports for the following projects: 

5.1. Source Apportionment Studies........................................................................................................................ 94 

Identification and quantification of the source(s) of high bromide and chloride concentrations 

at public water supply intakes downstream from wastewater treatment plants discharging 

treated hydraulic fracturing wastewater to surface waters 

5.2. Wastewater Treatability Studies.................................................................................................................. 101 

Assessment of the efficacy of common wastewater treatment processes on removing selected 

chemicals found in hydraulic fracturing wastewater 

5.3. Brominated Disinfection Byproduct Precursor Studies ..................................................................... 107 

Assessment of the ability of bromide and brominated compounds present in hydraulic 

fracturing wastewater to form brominated disinfection byproducts (Br-DBPs) during drinking 

water treatment processes 

5.4. Analytical Method Development .................................................................................................................. 112 

Development of analytical methods for selected chemicals found in hydraulic fracturing fluids 

or wastewater 

5.1. Source Apportionment Studies 


The EPA is combining data collected from samples of wastewater treatment facility discharges and 

receiving waters with existing modeling programs to identify the proportion of hydraulic fracturing 

wastewater that may be contributing to contamination at downstream public water system intakes. 

This work has been designed to help inform the answer to the research question listed in Table 36. 

Table 36. Secondary research questions addressed by the source apportionment research project. 







facilities 


The large national increase in hydraulic fracturing activity has generated large volumes of hydraulic 

fracturing wastewater for treatment and disposal or recycling. In some cases, states have allowed 

hydraulic fracturing wastewater to be treated by WWTFs with subsequent discharge to rivers. Most 

WWTFs are designed to filter and flocculate solids, as well as consume biodegradable organic 

species associated with human and some commercial waste. Very few facilities are designed to 

94



manage the organic and inorganic chemical compounds contained in hydraulic fracturing 

wastewater. 

Public water supply intakes may be located in river systems downstream from WWTFs and a 

variety of other industrial and urban discharges, and it is critical to evaluate sources of 

contamination at those drinking water intakes. Elevated bromide and chloride concentrations are 

of particular concern in drinking water sources due to the propensity of bromides to react with 

organic compounds to produce THMs and other DBPs during drinking water treatment processes 

(Plewa and Wagner, 2009). High TDS levels—including bromide and chloride—have been detected 

in the Monongahela River in 2008 and the Youghiogheny River in 2010 (Lee, 2011; Ziemkiewicz, 

2011). The source and effects of these elevated concentrations remains unclear. 

This project’s overall goal is to establish an approach whereby surface water samples may be 

evaluated to determine the extent to which hydraulic fracturing wastewaters (treated or untreated) 

may be present, and to distinguish whether any elevated bromide and chloride in those samples 

may be due to hydraulic fracturing or other activities. To accomplish this goal, the EPA is: (1) 

quantifying the inorganic chemical composition of discharges in two Pennsylvania river systems 

from WWTFs that accept and treat flowback and produced water, coal-fired utility boilers, acid 

mine drainage, stormwater runoff of roadway deicing material, and other industrial sources; (2) 

investigating the impacts of the discharges by simultaneously collecting multiple upstream and 

downstream samples to evaluate transport and dispersion of inorganic species; and (3) estimating 

the impact of these discharges on downstream bromide and chloride levels at PWS intakes using 

mathematical models. 


The “Quality Assurance Project Plan for Hydraulic Fracturing Wastewater Source Apportionment” 

provides a detailed description of the research approach (US EPA, 2012q). Briefly, water samples 

are being collected at five locations on two river systems; each river has an existing WWTF that is 

currently accepting hydraulic fracturing wastewater for treatment. Source profiles for significant 

sources such as hydraulic fracturing wastewater, WWTF effluent, coal-fired utility boiler 

discharge, acid mine drainage, and stormwater runoff from roadway deicing will be developed 

from samples collected from these sources during the study. Computer models will then be used 

to compare data from these river systems to chemical and isotopic composition profiles obtained 

from potential sources. 

Three two-week intensive sampling events were conducted to assess river conditions under 

different flow regimes: spring, summer, and fall 2012. As shown in Table 37, the amount of water in 

the river has historically been highest in the spring, resulting in the dilution of pollutants, and the 

summer and fall seasons typically have decreased stream flow, which may result in elevated 

concentrations due to less dilution (USGS, 2011a, b). USGS gauging stations near the WWTFs will be 

used to measure the flow rate during the three sampling periods. 

95



Table 37. Historical average of monthly mean river flow and range of monthly means from 2006 through 2011 for two 

rivers in Pennsylvania where the EPA collects samples for source apportionment research (USGS, 2011a, b). 

Month 

Average of Monthly Mean River Flow Range of Monthly Means from 2006 

from 2006 Through 2011 

Through 2011 

(cubic feet per second) 

(cubic feet per second) 

Allegheny River Blacklick Creek Allegheny River Blacklick Creek 

May 12,100 357 7,330–28,010 220.2–479.7 

July 5,740 134 2,164–10,840 65.8–198.2 

September 4,940 174 2,873–13,560 48.8–520.0 

During each sampling event, automatic water samplers (Teledyne Isco, model 6712) at each site 

collect two samples daily—morning and afternoon—based on the PWS and WWTF operations 

schedule. The samples are stored in the sampler for one to four days, depending on the site visit 

schedule. Each river is sampled in five locations, as shown in Table 38. The first sampling device 

downstream of the WWTF is far enough downstream to allow for adequate mixing of the WWTF 

effluent and river water. The second downstream sampling device is between the first 

downstream sampling location and the closest PWS intake. The locations of the samplers 

downstream of the WWTF also take into account the presence of other significant sources, such 

as coal-fired utility boiler and acid mine drainage discharges, and allow for the evaluation of their 

impacts. 

Table 38. Distance between sampling sites and wastewater treatment facilities on two rivers where the EPA collects 

samples for source apportionment research 

Site 

. 

Distance Between Sampling Sites (kilometers) 

Allegheny River 

Blacklick Creek 

Site 1 (upstream) -1.6 -1.2 

Site 2 (wastewater treatment facility) 0 0 

Site 3 (downstream) 12.2 2.7 

Site 4 (downstream) 44.1 43.1 

Site 5 (public water system intake) 52.3 88.6 

5.1.3.1. Sample Analyses 

The EPA will analyze the river samples and effluent samples according to existing EPA methods for 

the suite of elements and ions listed in Table 39. Inorganic ions (anions and cations) are being 

determined by ion chromatography. Inorganic elements are being determined using a combination 

of inductively coupled plasma optical emission spectroscopy for high-concentration elements and 

high-resolution magnetic sector field inductively coupled plasma mass spectrometry for low 

concentration elements. Additionally, the characteristic strontium (Sr) ratios ( 87 Sr/ 86 Sr; 0.7101– 

0.7121) in Marcellus Shale brines are extremely sensitive tracers, and elevated concentrations of 

readily water soluble strontium are present in the hydraulic fracturing wastewaters (Chapman et 

al., 2012). Isotope analyses for 87 Sr/ 86 Sr are being conducted on a subset (~20%) of samples by 

thermal ionization mass spectrometry to corroborate source apportionment modeling results. 

96



Table 39. Inorganic analyses and respective instrumentation planned for source apportionment research. The EPA 

will analyze samples from two rivers and effluent discharged from wastewater treatment facilities located on each 

river. Instruments used for analysis include high-resolution magnetic sector field inductively coupled plasma mass 

spectrometry (HR-ICP-MS), ion chromatography (IC), inductively coupled plasma optical emission spectroscopy 

(ICP-OES), and thermal ionization mass spectroscopy (TIMS). 

Element Instrument Used 

Element Instrument Used 

Ag* 

HR-ICP-MS 

Sb* 

HR-ICP-MS 

Al* 

ICP-OES 

Sc 

HR-ICP-MS 

As* 

HR-ICP-MS 

Se* 

HR-ICP-MS 

B* ICP-OES 

Si 

ICP-OES 

Ba* 

ICP-OES 

Sm 

HR-ICP-MS 

Be* 

HR-ICP-MS 

Sn 

HR-ICP-MS 

Bi 

HR-ICP-MS 

Sr* 

HR-ICP-MS 

Ca* 

ICP-OES 

Tb 

HR-ICP-MS 

Cd* 

HR-ICP-MS 

Th 

HR-ICP-MS 

Ce 

HR-ICP-MS 

Ti* 

ICP-OES 

Co* 

HR-ICP-MS 

Tl* 

HR-ICP-MS 

Cr* 

HR-ICP-MS 

U 

HR-ICP-MS 

Cs* 

HR-ICP-MS 

V* HR-ICP-MS 

Cu* ICP-OES, HR-ICP-MS 

W 

HR-ICP-MS 

Fe* ICP-OES, HR-ICP-MS 

Y 

HR-ICP-MS 

Gd 

HR-ICP-MS 

Zn* 

ICP-OES 

Ge 

HR-ICP-MS 

Isotope Ratio Instrument Used 

K* ICP-OES 

87 Sr/ 86 Sr* TIMS 

La 

HR-ICP-MS 

Ion 

Instrument Used 

Li* 

ICP-OES 

Ca 2+ * 

IC 

Mg* 

ICP-OES 

K + * 

IC 

Mn* ICP-OES, HR-ICP-MS 

Li + * 

IC 

Mo* 

HR-ICP-MS 

Mg 2+ * 

IC 

Na* 

ICP-OES 

+ 

NH 4 IC 

Nd 

HR-ICP-MS 

Na + * 

IC 

Ni* 

HR-ICP-MS 

Br - * 

IC 

P* ICP-OES 

Cl - * 

IC 

Pb* 

HR-ICP-MS 

F - * 

IC 

Pd 

HR-ICP-MS 

- 

NO 2 IC 

Pt 

HR-ICP-MS 

2 

NO 3 IC 

Rb 

HR-ICP-MS 

3 

PO 4 IC 

S* ICP-OES 

SO 2- 4 * 

IC 

* Chemicals detected in flowback and produced water. See Table A-3 in Appendix A. 

Although the majority of the species that are being quantified in this study have been identified in 

flowback or produced water, 60 the species relationships and relative quantities of the species in 

60 See Table A-3 in Appendix A. 

97



other sources (i.e., coal-fired utility boiler and acid mine drainage discharges) will differ (Chapman 

et al., 2012). This will allow the models described below to distinguish among the contributions 

from each source type. 

5.1.3.2. Source Apportionment Modeling 

The EPA is using the data gathered through the analyses described above to support source 

apportionment modeling. This source apportionment effort will use peer-reviewed receptor models 

to identify and quantify the relative contribution of different contaminant source types to 

environmental samples. 61 In this case, river samples collected near PWS intakes are being evaluated 

to discern the contributing sources (e.g., hydraulic fracturing wastewater or acid mine drainage) of 

bromide and chloride to those stream waters. Receptor models require a comprehensive analysis of 

environmental samples to provide a sufficient number of constituents to identify and separate the 

impacts of different source types. Analysis of major ions and inorganic trace elements (Table 39) 

will accomplish the needs for robust receptor modeling. Contaminant sources may be distinguished 

by unique ranges of chemical species and their concentrations, and the models provide quantitative 

estimates of the source type contributions along with robust uncertainty estimates. 

EPA-implemented models and commercial off-the-shelf software are being used to analyze the data 

from this particular study (e.g., Unmix, Positive Matrix Factorization, chemical mass balance). These 

models have previously been used to evaluate a wide range of environmental data for air, soil, and 

sediments (Cao et al., 2011; Pancras et al., 2011; Soonthornnonda and Christensen, 2008), and are 

now being used for emerging issues, such as potential impacts to drinking water from hydraulic 

fracturing. 


The EPA completed the two-week spring, summer, and fall intensive sampling periods beginning on 

May 16, July 20, and September 19, 2012, respectively. The EPA collected 206, 198, and 209 

samples during the spring, summer, and fall intensives, consisting of WWTF-treated discharge, 

river samples, raw hydraulic fracturing wastewater, and acid mine drainage. The data quality 

objectives (US EPA, 2012q) of 80% valid sample collection were met for both the spring (>85%) 

and summer (>96%) measurement intensives. Preparation work for the extraction and filtration 

of spring intensive samples for inductively coupled plasma optical emission spectroscopy and 

high-resolution magnetic sector field inductively coupled plasma mass spectrometry is ongoing. 

Table 40 shows the median discharge concentrations of chloride, bromide, sulfate, sodium, and 

conductivity in effluent from the two monitored WWTFs (prior to discharge and dilution in the 

rivers) during the spring sampling period; Table 40 also shows the conductivity of the effluent. 

Median chloride and sodium concentrations at Discharge A (Allegheny River) were almost 50% less 

than concentrations found at Discharge B (Blacklick Creek). High levels of sodium chloride 

(>20,000 milligrams per liter) are present in the discharge from both facilities (A and B). Bromide 

concentrations are roughly 35% lower at Discharge A than Discharge B. 

61 The receptor model, Positive Matrix Factorization, was peer-reviewed in 2007 (version 1.1) and 2011 (version 4.2), and 

Unmix (version 5.0) underwent peer review in 2007. 

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Table 40. Median concentrations of selected chemicals and conductivity of effluent treated and discharged from two 

wastewater treatment facilities that accept oil and gas wastewater. Discharge A is located on the Allegheny River and 

Discharge B is located on Blacklick Creek, both in Pennsylvania. The EPA collected samples beginning on May 16, 

2012. 

Measurement 

Median Concentration 

(milligrams per liter) 

Discharge A 

Discharge B 

Chloride 49,875 97,963 

Bromide 506 779 

Sulfate 679 976 

Sodium 20,756 38,394 

Conductivity (millisiemens per centimeter) 110 168 

The differences in the discharge concentrations are due to a combination of the treatment 

processes 

and 

unique regional chemical characteristics 

of oil and 

gas wastewater 

being treated at 

each 

of the facilities. Additionally, the 

discharge 

from the 

WWTFs 

is diluted 

into 

surface 

waters 

with very different median flows, with 

the 

USGS provisional 

median 

flows 

for the 

river 

sampling 

events 

reported as 15,158 

and 

2,531 

cubic feet per 

second 

for the 

Allegheny River 

in spring 

( May 

16–30, 2012) 

and summer 

(July 20– 

August 

3, 2012) 

, respectively 

( USGS, 2012a); 

and 

642 and 

35 

cubic feet per second for Blacklick Creek 

in 

spring ( May 

17– 

31, 2012) 

and summer 

( July 

21–August 

4, 2012), respectively 

(USGS, 2012b). 

The 

relative 

impact of these seasonal dilution scenarios from 

the WWTF 

discharges will 

be 

determined 

with 

the 

measured chemical species. 

5. 1. 5. 

Next 

Steps 

Analysis 

of 

field 

and 

source samples 

will continue in order to obtain the necessary data for source 

apportionment 

modeling. 

Once sample analyses 

are completed, data will be used 

as input 

to the 

receptor models described above to identify and 

quantify 

the 

sources of 

chloride and 

bromide 

at 

PWS intakes. 

5. 1. 6. 

Quality 

Assurance 

Summary 

The 

“ QAPP 

for 

Hydraulic Fracturing Wastewater Source Apportionment” was 

approved 

on April 17, 

2012 

(US 

EPA, 2012q). 

A TSA 

of the 

field sampling 

was 

conducted 

on 

May 

3, 2012, by 

the 

designated EPA QA Manager. There were two 

findings and 

two 

observations. 

The agreed-upon 

corrective actions 

were reported 

in writing 

to 

the researchers and management on May 

17, 2012, 

and 

have been 

implemented 

by 

the research 

team. 

One 

finding 

identified the 

need 

to 

verbally 

“ call back” measurement 

numbers 

between 

the sampler 

and scribe to 

confirm values when 

collecting 

short-term 

river 

measurements. 

The researchers 

instituted the verbal confirmation immediately in the field 

as suggested 

by the auditor. The 

second 

finding highlighted the need to accurately track 

the 

sample cooler 

temperature. A corrective action 

was implemented to improve the monitoring/recording of sample shipping cooler temperatures by 

ordering new National Institute of Standards and 

Technology 

traceable logging temperature 

loggers and keeping the loggers with 

the samples 

throughout the day 

in order to record 

accurate 

data of the temperatures 

at which the samples are stored and shipped. The new 

loggers were 

received and used in the field on May 8, 2012. 

99



During the audit, it was observed that the custody seals may not have offered a level of security 

necessary for the project. The field team had already identified this potential problem and had 

ordered different tamper-resistant seals before the field trip. The new seals (NIK Public Safety 

Tamperguard brand evidence tape) have been in use since they were received on May 10, 2012. 

The second observation during the audit was the need to document the reasoning of changes 

performed to standard operating procedures. The researchers have documented all the changes 

performed as well as the logic and reasoning of the changes in the field laboratory notebooks. Most 

modifications to the procedures were related to procedural adjustments made as a result of the 

field site characteristics, which were slightly different from the field site characteristics used to 

field-test the procedures in North Carolina. The documents also included updates to points of 

contact, references, and added text for clarification (e.g., river velocity measurements). Revisions 

reflecting these changes have been made to the QAPP and four SOPs based on the spring intensive 

field experience and the TSA. The revised version of the QAPP and four SOPs were approved on 

June 29, 2012. These updates do not impact the original data quality objectives. 

The researchers are following the QA procedures described in the QAPP and the standard operating 

procedures. In accordance to the QAPP, a TSA was performed on July 16 and 17, 2012, to evaluate 

laboratory operations. The designated EPA QA Manager reviewed the ion chromatography and 

high-resolution magnetic sector field inductively coupled plasma mass spectrometer analyses, data 

processing, storage, sample receiving and chain of custody procedures. The audit identified two 

observations and one best practice. One of the observations highlighted the need for a process that 

would ensure proper transcription of the data from the ion chromatography instrument to the 

report file. To reduce uncertainty and potential transcription errors, the analyst developed a 

process to export the data produced by the instrument in a text file instead of copying and pasting 

the data to a separate file. Another observation was the need to include performance evaluation 

samples in the analytical set. The performance evaluation samples will be analyzed in addition to 

the other quality controls already in place, which include blanks, duplicates, standard reference 

materials, and continuing calibration verification. The performance evaluation audit is being 

scheduled as specified in the QAPP. The blind performance evaluation samples will be analyzed 

with the regular samples and the data reported back to the QA Manager of the organization 

providing the blind performance evaluation samples. The best practice identified by the auditor 

was the tracking system, which uses a scanner and bar codes to track sampling bottles through the 

whole process: preparation, deployment to/from the field, sample analysis, and data reporting. The 

quality control (QC) procedures described in the QAPP have been followed in all instances. Besides 

the two TSAs performed and the performance evaluation audit, an ADQ is being coordinated by the 

designated EPA QA Manager. The source apportionment modeling will be described in a separate 

modeling QAPP. A TSA will be scheduled in 2013 for the modeling component of the study. 

100



5.2. Wastewater Treatability Studies 


The EPA is conducting laboratory experiments to assess the efficacy of conventional wastewater 

treatment processes on selected chemicals found in hydraulic fracturing wastewater to provide 

data to inform the research question posed in Table 41. The results of the water treatability 

experiments also complement the surface water modeling research project (see Section 4.2). 

Table 41. Secondary research questions addressed by the wastewater treatability laboratory studies. 





How effective are conventional POTWs and commercial treatment 

systems in removing organic and inorganic contaminants of concern 

in hydraulic fracturing wastewater 

5.2.2. Introduction 

Hydraulic fracturing wastewater, including flowback and produced water, is generally disposed of 

through underground injection in Class II UIC wells or treatment by a WWTF followed by surface 

water discharge. A generalized diagram for the onsite flow of water is given in Figure 24. A US 

Department of Energy report provides a state-by-state description of costs, regulations, and 

treatment/disposal practices for hydraulic fracturing wastes, including wastewater (Puder and Veil, 

2006). 

Wastewater may be treated at a WWTF, such as a POTW or centralized waste treatment facility 

(CWT). This project focuses on the efficacy of treatment processes at POTWs and CWTs, since 

discharge of treated wastewater to surface waters provides an opportunity for chemicals found in 

the effluent to be transported to downstream PWS intakes. This project will also explore treatment 

processes used for reuse of hydraulic fracturing wastewater. 

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Figure 24. Hydraulic fracturing wastewater flow in unconventional oil and gas extraction. Flowback and produced 

water (collectively referred to as “hydraulic fracturing wastewater”) is typically stored onsite prior to disposal or 

treatment. Hydraulic fracturing wastewater may be disposed of through Class II underground injection control (UIC) 

wells or through surface water discharge following treatment at wastewater treatment facilities, such as publicly 

owned treatment works or centralized waste treatment facilities. Wastewater may be treated on- or offsite prior to 

reuse in hydraulic fracturing fluids. 

5.2.2.1. Publicly Owned Treatment Works Treatment Processes 

Conventional POTW treatment processes are categorized into four groups: primary, secondary, 

tertiary, and advanced treatment. A generalized flow diagram is presented in Figure 25. 

Primary treatment processes remove larger solids and wastewater constituents that either settle or 

float. These processes include screens, weirs, grit removal, and/or sedimentation and flotation (e.g., 

primary clarification). Secondary treatment processes typically remove biodegradable organics by 

using microbial processes (e.g., “bioreactor” in Figure 25) in fixed media (e.g., trickling filters) or in 

the water column (e.g., aeration basins). There is typically another settling stage in the secondary 

treatment process where suspended solids generated in the aeration basin are removed through 

settling (“secondary clarifier” in Figure 25). In some systems, tertiary or advanced treatment (“filter 

and UV disinfection” in Figure 25) may be applied as a polishing step to achieve a particular end use 

water quality (e.g., for reuse in irrigation).The POTW then discharges the treated effluent to surface 

water, if recycling or reuse is not intended. Solid residuals formed as byproducts of the treatment 

processes may contain metals, organics, and radionuclides that were removed from the water. 

Residuals are typically de-watered and disposed of via landfill, land application, or incineration. 

102



Figure 25. Generalized flow diagram for conventional publicly owned works treatment processes. See the text for 

descriptions of primary, secondary, tertiary, and advanced treatment processes. 

The exact number of POTWs currently accepting hydraulic fracturing wastewater is not known. In 

Pennsylvania, where gas production from the Marcellus Shale is occurring, approximately 15 

POTWs were accepting hydraulic fracturing wastewater until approximately May 2011. In April 

2011, the Pennsylvania Department of Environmental Protection announced a request for 

Marcellus Shale natural gas drillers to voluntarily cease delivering their wastewater to the 15 

POTWs. The state also promulgated regulations in November 2011 that established monthly 

average limits (500 milligrams per liter TDS, 250 milligrams per liter chloride, 10 milligrams per 

liter total barium, and 10 milligrams per liter total strontium) for new and expanded TDS 

discharges (PADEP, 2011). These limits do not apply to the 15 facilities identified in the voluntary 

request or other grandfathered treatment plants. 

5.2.2.2. Commercial Waste Treatment Facility Processes 

Commercial processes for treating hydraulic fracturing wastewater include crystallization (zeroliquid 

discharge), thermal distillation/evaporation, electrodialysis, reverse osmosis, ion exchange, 

and coagulation/flocculation followed by settling and/or filtration. Some treatment processes are 

better able to treat high-TDS waters, which is a common property of hydraulic fracturing 

wastewater. Thermal processes are energy-intensive, but are effective at treating high-TDS waters 

103



and may be able to treat hydraulic fracturing wastewater with zero liquid discharge, leaving only a 

residual salt. Electrodialysis and reverse osmosis may be feasible for treating lower-TDS 

wastewaters. These technologies are not able to treat high-TDS waters (>45,000 milligrams per 

liter) and may require pre-treatment (e.g., coagulation and filtration) to minimize membrane 

fouling. 

Centralized waste treatment facilities can be used for pre-treatment prior to a POTW or, under an 

approved NPDES permit, can discharge directly to surface water (Figure 24). Commercial waste 

treatment processes will also result in some residual material that will require management and 

disposal. 

5.2.2.3. Reuse 

Gas producers are accelerating efforts to reuse and recycle hydraulic fracturing wastewater in some 

regions in order to decrease costs associated with procuring fresh water supplies, wastewater 

transportation, and offsite treatment and disposal. The EPA requested information on current 

wastewater management practices in the Marcellus Shale region from six oil and gas operators in 

May 2011. 62 Responses to the request for information indicated that reuse treatment technologies 

are similar, if not the same, to those used by WWTFs. Reuse technologies included direct reuse, 

onsite treatment (e.g., bag filtration, weir/settling tanks, third-party mobile treatment systems) and 

offsite treatment. Offsite treatment, in most instances, consisted of some form of stabilization, 

primary clarification, precipitation process, and secondary clarification and/or filtration. Specific 

details for offsite treatment methods were lacking as they are considered proprietary. 

Innovation in coupling various treatment processes may help reduce wastewater volumes and 

fresh water consumed in hydraulic fracturing operations. A challenge facing reuse technology 

development is treating water onsite to an acceptable quality for reuse in subsequent hydraulic 

fracturing operations. Key water quality parameters to control include TDS, calcium, and hardness, 

all of which play a major role in scale formation in wells. 

Recycling and reuse reduce the immediate need for treatment and disposal and water acquisition 

needs. There will likely be a need to treat and properly dispose of the final concentrated volumes of 

wastewater and residuals produced from treatment processes from a given area of operation, 

however. 


The EPA is examining the fate and transport of chemicals through conventional POTW treatment 

processes and commercial chemical coagulation/settling processes. The objective of this work is to 

identify the partitioning of selected chemicals between solid and aqueous phases and to assess the 

biodegradation of organic constituents. In addition, microbial community health will be monitored 

in the reactors to identify the point where biological processes begin to fail. Contaminants that can 

pass through treatment processes and impact downstream PWS intakes will be identified. 

62 Documents received pursuant to the request for information are available at http://www.epa.gov/region3/ 

marcellus_shale/. 

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Fate and Transport of Selected Contaminants in Wastewater Treatment Processes. The EPA will 

initially analyze the fate and transport of selected hydraulic fracturing–related contaminants in 

wastewater treatment processes, including conventional processes (primary clarifier, aeration 

basin, secondary clarifier), commercial processes (chemical precipitation/filtration and 

evaporation/distillation), and water reuse processes (pretreatment and filtration). The initial phase 

of this work will involve bench-scale fate and transport studies in a primary clarifier followed by 10 

liter chemostat reactors seeded with microbial organisms from POTW aeration basins. In benchscale 

work relevant to CWTs, similar fate and transport studies will be performed in chemical 

coagulation, settling, and filtration processes. 

A list of contaminants (Table 42) for initial treatability studies have been identified and are based 

on the list of hydraulic fracturing-related chemicals identified for initial analytical method 

development (Table 45 in Section 5.4). Table 42 may change as future information on toxicity and 

occurrence is gathered. In addition to monitoring the fate of the contaminants listed in Table 42 in 

treatment settings, impacts on conventional wastewater treatment efficiency will be monitored by 

examining changes in chemical oxygen demand, biological oxygen demand, and levels of nitrate, 

ammonia, phosphorus, oxygen, TDS, and total organic carbon in the aeration basin. 

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Table 42. Chemicals identified for initial studies on the adequacy of treatment of hydraulic fracturing wastewaters by 

conventional publicly owned treatment works, commercial treatment systems, and water reuse systems. Chemicals 

were identified from the list of chemicals needing analytical method development (Table 45). 

Target Chemical 

CASRN 

2,2-Dibromo-3 

nitrilopropionamide 

10222-01-2 

Acrylamide 79-06-1 

Arsenic* 7440-38-2 

Barium* 7440-39-3 

Benzene* 71-43-2 

Benzyl chloride 100-44-7 

Boron* 7440-42-8 

Bromide* 24959-67-9 

t-Butyl alcohol 75-65-0 

Chromium* 7440-47-3 

Diethanolamine 111-42-2 

Ethoxylated alcohols, C10–C14 66455-15-0 

Ethylbenzene* 100-41-4 

Ethylene glycol* 107-21-1 

Formaldehyde 82115-62-6 

Glutaraldehyde 111-30-8 

Target Chemical 

CASRN 

Isopropanol* 67-63-0 

Magnesium* 7439-95-4 

Manganese* 7439-96-5 

Methanol* 67-56-1 

Napthalene* 91-20-3 

Nonylphenol 68152-92-1 

Nonylphenol ethoxylate 68412-54-4 

Octylphenol 1806-26-4 

Octylphenol ethoxylate 26636-32-8 

Potassium* 7440-09-7 

Radium* 7440-14-4 

Sodium* 7440-23-5 

Strontium* 7440-24-6 

Thiourea 62-56-6 

Toluene* 108-88-3 

Uranium 7440-61-1 

Iron* 7439-89-6 Xylene* 1330-20-7 

* Chemicals reported to be in flowback and produced water. See Table A-3 in Appendix A. 

Characterization of Contaminants in Hydraulic Fracturing Wastewater Treatment Residuals. The EPA 

will examine the concentrations and chemical speciation of inorganic contaminants in treatment 

residuals. Residuals generated from the research described above will be analyzed for inorganic 

contaminant concentrations via EPA Method 3051A (Microwave Assisted Digestion) and 

inductively coupled argon plasma-optical emission spectrometry. Samples will also undergo 

analysis via X-ray absorption spectroscopy in order to assess oxidation state and chemical 

speciation of target contaminants. Organic contaminants will be analyzed via liquid or gas 

chromatography-mass spectrometry after accelerated solvent extraction of the solids. 


This research is currently in the planning stage. 


Initial studies will focus on establishing thresholds of TDS tolerance in chemostat bioreactors. Once 

the basic salt thresholds have been established, selected chemicals from the 26R forms will be 

added to the salt stock solutions. Salt concentrations will be kept below the thresholds where 

effects on the biological processes were observed. Potentially biodegradable pollutants (e.g., 

organics) will be measured, and the EPA will attempt to identify breakdown products. 

Constituents that are not biodegradable (e.g., elements and anions) will be tracked through the 

treatment process by analyzing system effluent using the appropriate EPA Methods and by 

106



analyzing residuals from the primary clarifier and the bioreactors. The results of these bench-scale 

studies will be applied to a pilot-scale system that would target compounds identified in benchscale 

studies as being the most problematic due to their lack of degradation or removal in the 

treatment process. 

For studies on commercial treatment systems using chemical addition/settling, the EPA plans to 

conduct jar tests that employ coagulants/flocculants at appropriate contact and settling times. The 

jar tests will be conducted at the bench-scale using actual hydraulic fracturing wastewater samples. 

The EPA will also attempt to mimic evaporative/distillation processes by using thermal treatment 

on actual hydraulic fracturing wastewater samples. Both the jar test samples and residuals from 

thermal treatment will be analyzed for the chemicals listed in Table 42. Elements in the residuals 

will also be characterized via X-ray diffraction and X-ray absorption microscopy. 


The initial QAPP, “Fate, Transport and Characterization of Contaminants in Hydraulic Fracturing 

Water in Wastewater Treatment Processes,” was submitted on December 20, 2011, and approved 

in August 2012 (US EPA, 2012q). 

Because project activities are still in an early stage, no TSA has been performed. A TSA will be 

performed once the project advances to the data collection stage. 

As results are reported and raw data are provided from the laboratories, ADQs will be performed to 

verify that the quality requirements specified in the approved QAPP were met. Data will be 

qualified if necessary, based on these ADQs. The results of the ADQs will be reported with the 

summary of results in the final report. 

5.3. Brominated Disinfection Byproduct Precursor Studies 

The EPA is assessing the ability of hydraulic fracturing wastewater to contribute to DBP formation 

in drinking water treatment facilities, with a particular focus on the formation of brominated DBPs. 

This work will inform the following research question listed in Table 43 and is complemented by 

the analytical method development for DBPs (see Section 5.4). 

Table 43. Secondary research questions potentially answered by studying brominated DBP formation from treated 

hydraulic fracturing wastewater. 







facilities 

5.3.1. Introduction 

Wastewaters from hydraulic fracturing processes typically contain high concentrations of TDS, 

including significant concentrations of chloride and bromide. These halogens are difficult to remove 

from wastewater; if discharged from treatment works, they can elevate chloride and bromide 

concentrations in drinking water sources. Upon chlorination at a drinking water treatment facility, 

chloride and bromide can react with naturally occurring organic matter (NOM) in the water and 

107



lead to the formation of DBPs. Because of their carcinogenicity and reproductive and 

developmental affects, the maximum contaminant levels (MCLs) of the DBPs bromate, chlorite, 

haloacetic acids, and total THMs in finished drinking water are regulated by the National Primary 

Drinking Water Regulations. 63 Table 44 summarizes the DBPs regulated and their corresponding 

MCLs. 

Increased bromide concentrations in drinking water resources can lead to greater total THM 

concentrations on a mass basis and may make it difficult for some PWSs to meet the regulatory 

limits of total THM listing in Table 44 in finished drinking water. As a first step, this project is 

examining the formation of brominated THMs, including bromoform (CHBr 3), 

dibromochloromethane (CHClBr 2), and bromodichloromethane (CHCl 2Br), during drinking water 

treatment processes. The formation of haloacetic acids (HAAs) and nitrosamines during drinking 

water treatment processes is also being investigated. 64 

Reactions of brominated biocides used in hydraulic fracturing operations with typical drinking 

water disinfectants associated with chlorination or chloramination are also being explored. 65 

Brominated biocides are often used in fracturing fluids to minimize biofilm growth. The objective of 

this work is to assess the contribution, if any, to brominated DBP formation and identify 

degradation pathways for brominated biocides. 

63 Authorized by the Safe Drinking Water Act. 

64 Nitrosamines are byproducts of drinking water disinfection, typically chloramination, and currently unregulated by the 

EPA. Data collected from the second Unregulated Contaminant Monitoring Rule indicate that nitrosamines are frequently 

being found in PWSs. Nitrosamines are potentially carcinogenic. 

65 Chlorination and chloramination are common disinfection processes used for drinking water. 

108



Table 44. Disinfection byproducts regulated by the National Primary Drinking Water Regulations. 

Disinfection Byproduct 

Maximum Contaminant Level Maximum Contaminant Level † 

Goal* (milligrams per liter) 


Total Trihalomethanes 

Bromodichloromethane 

Zero 

Bromoform 

Zero 

0.080 as an annual average 

(sum of the concentrations of all 

Dibromochloromethane 

0.060 

four trihalomethanes) 

Chloroform 0.070 

Haloacetic Acids 

Dichloroacetic acid 

Zero 

Trichloroacetic acid 0.020 

Monochloroacetic acid 0.070 0.060 as an annual average 

Bromoacetic acid 

Regulated with this group but has (sum of the concentrations of all 

no MCL goal 

five haloacetic acids) 

Dibromoacetic acid 

Regulated with this group but has 

no MCL goal 

Bromate Zero 0.010 as an annual average 

Chlorite 0.80 1.0 

* A maximum contaminant level goal is the non-enforceable concentration of a contaminant in drinking water below 

which there is no known or expected risk to health; they are established under the Safe Drinking Water Act. 

† 

A maximum contaminant level (MCL) is an enforceable standard corresponding to the highest level of a 

contaminant that is allowed in drinking water. MCLs are set as close to MCL goals as feasible using the best 

available treatment technology and taking cost into consideration. MCLs are set under the Safe Drinking Water Act 

and apply only to water delivered by public water supplies (water supplies that serve 15 or more service connections 

or regularly serves an average of 25 or more people daily at least 60 days out of the year) (40 CFR 141.2). 

It is important to note that hydraulic fracturing wastewater can potentially contain other 

contaminants in significant concentrations that could affect human health. The EPA identified the 

impacts of elevated bromide and chloride levels in surface water from hydraulic fracturing 

wastewater discharge as a priority for protection of public water supplies. This project will 

ultimately provide PWSs with information on the potential for brominated DBP formation in 

surface waters receiving discharges from WWTFs. 


This research will (1) analyze and characterize hydraulic fracturing wastewater for presence of 

halides, (2) evaluate the effects of high TDS upon chlorination of surface water receiving discharges 

of treated hydraulic fracturing wastewater, and (3) examine the reactions of brominated biocides 

subjected to chlorination during drinking water treatment. Selected analytes for characterizing 

hydraulic fracturing wastewater include nitrosamines and the halide anions chloride, bromide, and 

iodide—ions that are the likeliest to form DBPs (Richardson, 2003), including THMs and HAAs. 

Hydraulic fracturing wastewater samples have been obtained from several sources in Pennsylvania. 

The quantification of background concentrations of halides in the samples follows EPA Method 

300.1 (rev. 1) and the modified version of the method using mass spectrometry detection for 

bromide and bromate (discussed in Section 5.4). The samples are also being analyzed for the 

presence of DBPs, including THMs (EPA Method 551.1), HAAs (EPA Method 552.1), and N 

109



nitrosamines (EPA Method 521), as well as elemental composition, anion concentration, TDS, and 

total organic carbon. 

Three treatments are being applied to high-TDS wastewater samples: (1) samples will be blended 

with deionized water at rates that mimic discharge into varying flow rates of receiving water in 

order to account for dilution effects; (2) samples will be blended with deionized water with NOM 

additions at concentration ranges typically found in surface waters; and (3) samples will be 

blended with actual surface water samples from rivers that receive treated hydraulic fracturing 

wastewater discharges. All samples will be subjected to formation potential experiments in the 

presence of typical drinking water disinfectants associated with chlorination or chloramination. 

Formation potential measures will be obtained separately for THMs, HAAs, and nitrosamines. 

Disinfection byproduct formation in surface water samples will be compared with DBP formation in 

deionized water as well as deionized water fortified with several NOM isolates from different water 

sources in order to examine the effects of different NOM on DBP formation. 66 

The brominated biocides 2,2-dibromo-3-nitropropionamide and 2-bromo-2-nitrol-1,3-propanediol, 

employed in hydraulic fracturing processes, are being subjected to chlorination conditions 

encountered during drinking water treatment. These experiments should provide insight on the 

potential formation of brominated THMs from brominated biocides. Effects of chlorination on the 

brominated biocides are also being monitored. 


Work has begun on total THM formation studies to identify potential problems with analysis (EPA 

Method 551.1) due to the high TDS levels typical in hydraulic fracturing wastewater. Wastewater 

influent and effluent samples were obtained from researchers involved in the source 

apportionment studies (Section 5.1) at two CWTs in Pennsylvania that are currently accepting 

hydraulic fracturing wastewater for treatment via chemical addition and settling. For this 

preliminary research, samples were diluted 1:100 with deionized water and equilibrated with 

sodium hypochlorite until a 2 milligrams per liter concentration of sodium hypochlorite was 

achieved (a typical disinfectant concentration for finished water from a PWS). The samples are 

being analyzed for pH, metals, TDS, total suspended solids, total organic content, and selected 

anions. 

Efforts to identify and quantify the parent brominated biocides using liquid chromatography/mass 

spectrometry methods have been unsuccessful to date, possibly due to poor ionization of the 

brominated molecules. The biocide samples subject to chlorination have been prepared for analysis 

of THMs. 

66 The concentration, chemical composition, and reactivity of NOM varies by geographic location due to factors such as 

presence and type of vegetation, physical and chemical properties of the surrounding soil and water, biological activity, 

and human activity among many others. 

110




When the preliminary work on potential analytical effects from high TDS on total THM recovery is 

complete, a series of experiments to assess the potential formation of DBPs during chlorination will 

be run on the following samples: 

• Deionized water 

• Deionized water, varying concentrations of NOM 

• Deionized water plus TDS 

• Deionized water plus TDS and NOM 

• Hydraulic fracturing wastewater 

This series of samples will allow THM formation comparisons between hydraulic fracturing 

wastewater samples and less complex matrices. Dilutions will be made on the samples based on 

effluent discharge rates for existing WWTFs and receiving water flow rates. The samples will 

undergo chlorination and be sub-sampled over time (e.g., 0 to 120 minutes). Chloride to bromide 

ratios will be set at 50:1, 100:1, and 150:1 to encompass the range of conditions that may be found 

in surface waters impacted by varying concentrations of chloride and bromide. The sub-samples 

will be analyzed for individual THMs and formation kinetics will be determined. The EPA 

anticipates obtaining data for the formation of HAAs and nitrosamines, though THMs are the 

priority at this time. 


The initial QAPP, “Formation of Disinfection By-Products from Hydraulic Fracturing Fluids,” was 

submitted on June 28, 2011, and approved on October 5, 2011 (US EPA, 2011h). On June 7, 2012, an 

addendum was submitted and approved on June 28, 2012; this provided more details on 

modifications to EPA Method 300.1 for optimizing bromide/bromate recoveries in high-salt 

matrices. There are no deviations from existing QAPPs to report at this time. 

A TSA was performed on March 15, 2012, for this research project. Five findings were observed, 

related to improved communication, project documentation, sample storage, and QA/QC checks. 

Recommended corrective actions were accepted to address the findings. Since the TSA was 

performed before data generation activities, no impact on future reported results is expected. It is 

anticipated that a second TSA will be performed as the project progresses. 

As raw data are provided from the laboratories and results are reported, ADQs will be performed to 

verify that the quality requirements specified in the approved QAPP have been met. Data will be 

qualified if necessary based on these ADQs. Audits of data quality are scheduled for the first quarter 

of 2013 (none have been performed yet). The results of these ADQs will be reported with the 

summary of results in the final report. 

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5.4. Analytical Method Development 


Sample analysis is an integral part of the EPA’s Plan to Study the Potential Impacts of Hydraulic 

Fracturing on Drinking Water Resources (US EPA, 2011e) and is clearly specified in research plans 

being carried out for the study’s retrospective case studies, prospective case studies, and laboratory 

studies. The EPA requires robust analytical methods to accurately and precisely determine the 

composition of hydraulic fracturing-related chemicals in ground and surface water, flowback and 

produced water, and treated wastewater. 


Analytical methods enable accurate and precise measurement of the presence and quantities of 

different chemicals in various matrices. Since the quantification of the presence or absence of 

hydraulic fracturing-related chemicals will likely have substantial implications for the conclusions 

of the study, it is important that robust analytical methods exist for chemicals of interest. 

In many cases, standard EPA methods that have been designed for a specific matrix or set of 

matrices can be used for this study. Standard EPA methods are peer-reviewed and officially 

promulgated methods that are used under different EPA regulatory programs. For example, EPA 

Method 551.1 is being used to detect THMs as part of the Br-DBP research project (see Section 5.3) 

and EPA Method 8015D is being used to detect diesel range organics in ground and surface water 

samples collected as part of the retrospective case studies (see Chapter 7). 

In other cases, standard EPA methods are nonexistent for a chemical of interest. In these situations, 

methods published in the peer-reviewed literature or developed by consensus standard 

organizations (e.g., the American Society for Testing and Materials, or ASTM) are used. However, 

these methods are rarely developed for or tested within matrices associated with the hydraulic 

fracturing process. In rare, but existing cases, where no documented methods exist, researchers 

generally develop their own methods for determining the concentrations of certain chemicals of 

interest. For these latter two situations, the analytical methods chosen must undergo rigorous 

testing, verification, and potential validation to ensure that the data generated they generate are of 

known and high quality. The EPA has identified selected chemicals found in hydraulic fracturing 

fluids and wastewater for the development and verification of analytical methods. 


5.4.3.1. Chemical Selection 

Hydraulic fracturing-related chemicals include chemicals used in the injected fracturing fluid, 

chemicals found in flowback and produced water, and chemicals resulting from the treatment of 

hydraulic fracturing wastewater (e.g., chlorination or bromination at wastewater treatment 

facilities). Some of these chemicals are present due to the mobilization of naturally occurring 

chemicals within the geologic formations or through the degradation or reaction of the injected 

chemicals in the different environments (i.e., subsurface, surface and wastewater). The EPA has 

identified over 1,000 chemicals that are reported to be used in fracturing fluids or found in 

hydraulic fracturing wastewaters (see Appendix A); these range from the inert and innocuous, such 

as sand and water, to reactive and toxic chemicals, like alkylphenols and radionuclides. 

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To help choose chemicals for analytical method testing, a group of EPA researchers and analytical 

laboratory chemists discussed the factors most important to their research needs and to the overall 

study. The following criteria were developed to identify a subset of the chemicals listed in Appendix 

A for initial analytical method testing activities: 

• Frequency of occurrence 67 in hydraulic fracturing fluids and wastewater 

• Toxicity 68 

• Mobility in the environment (expected fate and transport) 

• Availability of instrumentation/detection systems for the chemical 

Table 45 lists the chemicals selected for analytical method testing and development. It includes 14 

different classes of chemicals, 51 specifically identified elements or compounds, six groups of 

compounds (e.g., ethoxylated alcohols and light petroleum distillates), and two related physical 

properties (gross α and gross β analyses associated with radionuclides). The EPA will continually 

review Table 45 and add new chemicals as needed. 

67 Occurrence information was gathered from the US House of Representatives report Chemicals Used in Hydraulic 

Fracturing (2011) (USHR, 2011)and Colborn et al. (2011). Chemicals with high frequencies were considered for inclusion. 

However, some high-frequency chemicals were ultimately not included in the EPA’s priority list of chemicals of interest. 

For example, while silica or silicon dioxide is often near the top of lists in terms of frequency of occurrence, this likely 

refers to the sand that is used as a proppant during the hydraulic fracturing process. Additionally, certain chemicals, such 

as hydrogen chloride or sulfuric acid, no longer exist as the initial compounds once dissolved in water and often react 

with other compounds. As a result, these chemicals, and others, were not added to the list. 

68 Colborn et al. (2011) provided toxicity information compiled from MSDS from industry and government agencies and 

compared the chemicals in their list with toxic chemical databases, such as TOXNET and the Hazardous Substances 

Database. 

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Table 45. Chemicals identified for analytical method testing activities. Selection criteria for the chemicals included, but were not limited to, frequency of occurrence 

in fracturing fluids and wastewater, toxicity, environmental mobility, and availability of detection systems for the chemical. 

Chemical Class Chemical Name(s) CASRN Purpose in Hydraulic Fracturing Reason Selected 

Propargyl alcohol 107‐19‐7 

Alcohols 

Methanol 67‐56‐1 Corrosion inhibitor 

Isopropanol 67‐63‐0 

Toxicity, frequency of use 

t‐Butyl alcohol 75‐65‐0 Byproduct of t‐butyl hydroperoxide 

Aldehydes 

Glutaraldehyde 111‐30‐8 Biocide 

Formaldehyde 50‐00‐0 Biocide 


Alkylphenols 

Octylphenol 27193-28-8 

Nonylphenol 84852-15-3 

Surfactant 


Alkylphenol Octylphenol ethoxylate 9036-19-5 

ethoxylates Nonylphenol ethoxylate 26027-38-3 

Surfactant 

Frequency of use 

Thiourea 62‐56‐6 Corrosion inhibitor Toxicity 

Amides 

Acrylamide 79‐06‐1 Friction reducer Toxicity, frequency of use, 

requested by EPA 

2,2‐Dibromo‐3‐nitrilopropionamide 10222‐01‐2 Biocide 

researchers 

Amines (alcohol) Diethanolamine 111-42-2 Foaming agent Frequency of use 

Aromatic 

hydrocarbons 

BTEX, naphthalene, benzyl 

chloride, light petroleum 

hydrocarbons 

Carbohydrates Polysaccharides Byproduct 

Disinfection 

byproducts 

Ethoxylated 

alcohols 

Trihalomethanes, haloacetic acids, 

N-nitrosamines* 

Ethoxylated alcohols, 

C8–10 and C12–18 

Gelling agents, solvents 

Byproduct 

Toxicity, frequency of use, 

requested by EPA 

researchers 

Requested by EPA 

researchers 

Toxicity 

68954-94-9 Surfactant Frequency of use 


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Chemical Class Chemical Name(s) CASRN Purpose in Hydraulic Fracturing Reason Selected 

Ethylene glycol 107‐21‐1 

Diethylene glycol 111‐46‐6 

Crosslinker, breaker, scale inhibitor 

Triethylene glycol 112-27-6 

Glycols 

Frequency of use 

Tetraethylene glycol 112-60-7 

2‐Methoxyethanol † 109‐86‐4 

2-Butoxyethanol † 111-76-2 

Foaming agent 

Halogens Chloride 16887‐00‐6 Brine carrier fluid, breaker Frequency of use 

Barium 7440‐39‐3 Mobilized during hydraulic fracturing 

Inorganics 

Strontium 7440‐24‐6 Mobilized during hydraulic fracturing Toxicity, frequency of use 

of potassium and sodium 

Boron 7440‐42‐8 Crosslinker 

salts, mobilization of 

Sodium 7440‐23‐5 Brine carrier fluid, breaker 

naturally occurring ions 

Potassium 7440‐09‐7 Brine carrier fluid 

Gross α 

Gross β 

Toxicity, mobilization of 

Radionuclides Radium 13982‐63‐3 Mobilized during hydraulic fracturing 

naturally occurring ions 

Uranium 7440‐61‐1 

Thorium 7440‐29‐1 

* See Section 5.3. 

† 

These compounds are chemically similar to glycols and are analyzed using the same methods. 

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5.4.3.2. Analytical Method Testing and Development 

Method Development. The EPA’s process for analytical method development is shown in Figure 26. 

In the first step, an existing base method is identified for the specific chemical(s) of interest in a 

given matrix. Base methods may include promulgated, standard methods or, if no standard 

methods are available, methods existing in peer-reviewed literature or developed through a 

consensus standard organization. 

Select base 

analytical method 

Accept base method 

Yes 

QA/QC testing: 

Does the method meet 

specified QA/QC acceptance 

criteria 

No 

Identify potential 

reasons for QA/QC failing 

acceptance criteria 

Accept modified base 

method and prepare 

standard operating 

procedure (SOP) 

Modify method to correct 

cause of interference 

No 

Major modifications 

to method 

Yes 

Repeat testing: 

Does the modified method 

meet specified QA/QC 

acceptance criteria 

No 

Modify method to 

correct cause of 

failure to meet criteria 

Yes 

No, repeatedly 

Prepare SOP for 

method 

Develop new method if 

existing method cannot be 

modified to meet QA/QC 

acceptable criteria 

Figure 26. Flow diagram of the EPA’s process leading to the development of modified or new analytical methods. 

Analytical methods may exist for specific chemicals or for a general class of chemicals (e.g., 

alcohols). Table 46 lists the base methods identified for the 14 chemical classes shown in Table 45. 

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Table 46. Existing standard methods for analysis of selected hydraulic fracturing-related chemicals listed in Table 45. 

The EPA will analyze samples using existing methods to determine if the procedure meets the quality assurance 

criteria for the current study. 

Chemical Class 

Standard Method* 

Alcohols 

SW-846 Methods 5030 and 8260C 

Aldehydes SW-846 Method 8315 

Alkylphenols 

No standard method 

Alkylphenol ethoxylates 


Amides 

SW-846 Methods 8032A 

Amines (alcohols) 


Aromatic hydrocarbons 

SW-846 Methods 5030 and 8260C 

Carbohydrates 


Disinfection byproducts DWA Methods 521, 551, and 552 

Ethoxylated alcohols ASTM D7485-09 

Glycols 

Region 3 Draft Standard Operating Procedure 

Halogens 

SW-846 Method 9056A 

Inorganic elements 

SW-846 Methods 3015A and 6020A 

Radionuclides SW-846 Method 9310 

* DWA methods can be found at http://water.epa.gov/scitech/methods/cwa/index.cfm. SW-846 

Methods can be found at http://www.epa.gov/epawaste/hazard/testmethods/sw846/online/ 

index.htm. 

Once a candidate base method is selected, 69 an initial QA/QC round of testing is conducted. Testing 

occurs first with spiked laboratory water samples to familiarize the analyst with the method 

procedure, eliminate any potential matrix interferences, and determine various QA/QC control 

parameters, such as sensitivity, bias, precision, spike recovery, and analytical carry-over potential 

(sample cross-contamination). The results from the initial QA/QC testing are examined to 

determine if they meet the acceptance criteria specified in the QAPP (US EPA, 2011g) and thus are 

sufficient to meet the needs of the research study. Some of the key QA/QC samples examined 

include: 

• Standard and certified reference materials (where available) for bias 

• Matrix and surrogate spikes for bias (when reference materials are not available) and 

matrix interferences 

• Replicates for precision 

• Blanks for analytical carry-over 

If an acceptance criterion for any of the QA/QC samples is not met, the sample is typically re-run to 

ensure that the result is not a random event. If an acceptance criterion is repeatedly not met, a 

69 Additional information on selecting a base method can be found in the QAPP, “Quality Assurance Project Plan for the 

Chemical Characterization of Select Constituents Relevant to Hydraulic Fracturing,” found at 

http://www.epa.gov/hfstudy/qapps.html. 

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systematic problem is indicated, and method modification is undertaken to help reduce or 

eliminate the problem. 

The method modification process can take many forms, depending on the specific circumstances, 

and may include changing sample preparation and cleanup techniques, solvents, filters, gas flow 

rates, temperature regimes, injector volumes, chromatographic columns, analytical detectors, etc. 

Once the method modification process is complete, the analysis is repeated as described above 

using spiked laboratory water samples. If the new QA/QC sample results meet the acceptance 

criterion, the method modification is deemed to have been successful for that matrix and an 

updated SOP is prepared. Additional testing in more complex water matrices will continue, if 

appropriate. 

If testing and modification of the identified base method fails to accurately and precisely quantify 

the chemical of interest and/or fails to have the sensitivity required by the research program, the 

EPA may undertake new method development activities. 

Method Verification. Method verification determines the robustness of successfully tested and 

modified analytical methods. This involves the preparation of multiple blind spiked samples (i.e., 

samples whose concentrations are only known to the sample preparer) by an independent chemist 

(i.e., one not associated with developing the method under testing and verification) and the 

submission of the samples to at least three other analytical laboratories participating in the 

verification process. Results from the method verification process can lead to either the acceptance 

of the method or re-evaluation and further testing of the method (US EPA, 1995). 

Method Validation. The final possible step in analytical method testing and development is method 

validation. Method validation involves large, multi-laboratory, round robin studies and is generally 

conducted by the EPA program offices responsible for the publication and promulgation of 

standard EPA methods. 

5.4.4. Status, Preliminary Data, and Next Steps 

Method development, testing, and verification are being conducted according to the procedures 

outlined in two QAPPs: “Quality Assurance Project Plan for the Chemical Characterization of Select 

Constituents Relevant to Hydraulic Fracturing” (US EPA, 2011g) and “Quality Assurance Project 

Plan for the Inter-Laboratory Verification and Validation of Diethylene Glycol, Triethylene Glycol, 

Tetraethylene Glycol, 2-Butoxyethanol and 2-Methoxyethanol in Ground and Surface Waters by 

Liquid Chromatography/Tandem Mass Spectrometry” (US EPA, 2012r). 

5.4.4.1. Glycols and Related Compounds 

Glycols (diethylene glycol, triethylene glycol, and tetraethylene glycol) and the chemically related 

compounds 2-butoxyethanol and 2-methoxyethanol are frequently used in hydraulic fracturing 

fluids and not naturally found in ground water. Thus, they may serve as reliable indicators of 

contamination of ground water from hydraulic fracturing activities. EPA Method 8015b is the gas 

chromatography-flame ionization detector method typically used to analyze for glycols; however, 

the sensitivity is not sufficient for the low-level analysis required for this project. Therefore, the 

EPA’s Region 3 Environmental Science Center developed a method for the determination and 

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quantification of these compounds using liquid chromatography-tandem mass spectrometry. The 

method is based on ASTM D7731-11e1 and EPA SW-846 Method 8321. The EPA is currently 

verifying this method to determine its efficacy in identifying and quantifying these compounds in 

drinking water and other water matrices associated with the hydraulic fracturing process. 

5.4.4.2. Acrylamide 

Acrylamide is often used as a friction reducer in injected hydraulic fracturing fluids (GWPC, 

2012b). EPA SW-846 Methods 8316 and 8032A are both suitable methods for the analysis of 

acrylamide. Method 8316 involves analysis by high-performance liquid chromatography with 

ultraviolet detector at 195 nanometers, with a detection level of 10 micrograms per liter. This 

short wavelength, however, is not very selective for acrylamide (i.e., interferences are likely), and 

the sensitivity is not adequate for measurements in water. Method 8032A involves the 

bromination of acrylamide, followed by gas chromatography-mass spectrometry analysis. This 

method is much more selective for acrylamide, and detection limits are much lower (0.03 

micrograms per liter). However, in complex matrices (e.g., hydraulic fracturing wastewater), the 

accuracy and precision of acrylamide analysis may be limited by poor extraction efficiency and 

matrix interference. 

To avoid reactions with other compounds present in environmental matrices and to lower the 

detection limit, the EPA is developing a new analytical method for the determination of acrylamide 

at very low levels in water containing a variety of additives. The method currently under 

development involves solid phase extraction with activated carbon followed by quantitation by 

liquid chromatography-tandem mass spectrometry using an ion exclusion column. The EPA has 

begun the multi-laboratory verification of the method. 

5.4.4.3. Ethoxylated Alcohols 

Surfactants are often added to hydraulic fracturing fluids to decrease liquid surface tension and 

improve fluid passage through pipes. Most of the surfactants used are alcohols or some derivative 

of an ethoxylated compound, typically ethoxylated alcohols. Many ethoxylated alcohols and 

ethoxylated alkylphenols biodegrade in the environment, but often the degradation byproducts 

are toxic (e.g., nonylphenol, a degradation product of nonylphenol ethoxylate, is an endocrine 

disrupting compound) (Talmage, 1994). No standard method currently exists for the 

determination of ethoxylated alcohols; therefore, the EPA is developing a quantitative method for 

ethoxylated alcohols. ASTM Method D 7458-09 and USGS Method Number O1433-01 were used 

as starting points for this method development effort; both of these methods involve solid-phase 

extraction followed by liquid chromatography-tandem mass spectrometry quantitation. These 

methods both allow the analysis of nonylphenol diethoxylate and alkylphenols, but there are 

currently no standard methods for the analysis of the full range of nonylphenol ethoxylate 

oligomers (EO 3–EO 20) or alcohol ethoxylate oligomers (C 12–15EO x, where x = 2–20). This method 

SOP is being prepared and will be followed by method verification. 

5.4.4.4. Disinfection Byproducts 

Flowback and produced water can contain high levels of TDS, which may include bromide and 

chloride (US EPA, 2012d). In some cases, treatment of flowback and produced water occurs at 

WWTFs, which may be unable to effectively remove bromide and chloride from hydraulic 

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fracturing wastewater before discharge. The presence of bromide ions in source waters undergoing 

chlorination disinfection may lead to the formation of brominated DBPs—including bromate, THMs, 

and HAAs—upon reaction with natural organic material (Richardson, 2003). Brominated DBPs are 

considerably more toxic than corresponding chlorinated DBPs (Plewa et al., 2004; Richardson et al., 

2007) and have higher molecular weight. Therefore, on an equal molar basis, brominated DBPs will 

have a greater concentration by weight than chlorinated DBPs, hence leading to a greater likelihood 

of exceeding the total THM and HAA MCLs that are stipulated in weight concentrations (0.080 and 

0.060 milligrams per liter, respectively). Accordingly, it is important to assess and quantify the 

effects of flowback and produced water on DBP generation (see Section 5.3). 

Analytical methods for the measurement of bromide and bromate in elevated TDS matrices are 

currently being developed. EPA Method 300.1 is being modified to use a mass spectrometer rather 

that an electroconductivity detector, which is unable to detect bromide and bromate in the 

presence high anion concentrations (SO 4 

2-, NO 2 

-, NO 3 

-, F - , Cl - ). The mass spectrometer allows 

selected ion monitoring specifically for the two natural stable isotopes of bromine ( 79 Br and 81 Br), 

with minimal interference from other anions in the high-salt matrix. Interference of the bromide 

and bromate response in the mass spectrometer are being assessed by comparing instrument 

responses to solutions of bromide and bromate in deionized water with selected anions over a 

range of ratios typically encountered in hydraulic fracturing wastewater samples (US EPA, 2012d). 

Interference concentration thresholds are being established, and a suitable sample dilution method 

is being developed for the quantification of bromide and bromate in actual hydraulic fracturing 

wastewater samples. Method detection limits and lowest concentration minimum reporting levels 

are being calculated for bromide and bromate in high-salt matrices according to EPA protocols (US 

EPA, 2010h). 

5.4.4.5. Radionuclides 

Gross α and β analyses measure the radioactivity associated with gross α and gross β particles 

that are released during the natural decay of radioactive elements, such as uranium, thorium, and 

radium. Gross α and β analyses are typically used to screen hydraulic fracturing wastewater in 

order to assess gross levels of radioactivity. This information can be used to identify waters 

needing radionuclide-specific characterization. The TDS and organic content characteristic of 

hydraulic fracturing wastewater, however, interferes with currently accepted methods for gross 

α and β analyses. The QAPP for testing and developing gross α and β analytical methods is in 

development, and, after it is approved, work will begin. 

5.4.4.6. Inorganic Chemicals 

In addition to the potential mobilization of naturally occurring radioactive elements, hydraulic 

fracturing may also release other elements from the fractured shales, tight sands, and coalbeds, 

notably heavy metals such as barium and strontium. Inorganic compounds may also be added to 

hydraulic fracturing fluids to perform various functions (e.g., cross-linkers using borate salts, brine 

carrier fluids using potassium chloride, and pH-adjusting agents using sodium carbonates) (US EPA, 

2011e). Due to the injection or release of naturally occurring metals in unknown quantities, it is 

essential that analytical methods for the determination of inorganic elements in waters associated 

with hydraulic fracturing be robust and free from interferences that may mask true concentrations. 

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The EPA SW-846 Method 6010, employing inductively coupled plasma-optical emission 

spectrometry, will be used as a base method for major elements while SW-846 Method 6020 based 

on inductively coupled plasma-mass spectrometry will be used as a base method for trace 

elements. 70 These methods will be tested and potentially modified for detection of major and trace 

elements in hydraulic fracturing wastewater. 


Three QAPPs have been prepared for the analytical method testing research program. The first 

QAPP, “Quality Assurance Project Plan for the Chemical Characterization of Select Constituents 

Relevant to Hydraulic Fracturing” (US EPA, 2011g), is the broad general QAPP for the methods 

development research project. The QAPP was approved on September 1, 2011. In order to 

maintain high QA standards and practices throughout the project, a surveillance audit was 

performed on November 15, 2011. The purpose of the surveillance audit was to examine the 

processes associated with the in-house extraction of ethoxylated alcohols. Three 

recommendations were identified and have been accepted. 

The second QAPP, “Formation of Disinfection By-Products from Hydraulic Fracturing Fluid 

Constituents Quality Assurance Project Plan,” (US EPA, 2011h), provides details on modifications to 

EPA Method 300.1 for optimizing bromide/bromate recoveries in high-salt matrices. The QAPP was 

approved on October 5, 2011, and the addendum for bromide/bromate analytic method 

development was approved on June 28, 2012. There are no deviations from existing QAPPs to 

report at this time. A surveillance audit was performed in March 2011 before the analytical method 

addendum (June 28, 2012); therefore, the analytical method development for bromide/bromate 

has not yet been audited. 

The third QAPP, “Quality Assurance Project Plan for the Inter-Laboratory Verification and 

Validation of Diethylene Glycol, Triethylene Glycol, Tetraethylene Glycol, 2-Butoxyethanol and 2 

Methoxyethanol in Ground and Surface Waters by Liquid Chromatography/Tandem Mass 

Spectrometry” (US EPA, 2012r), was prepared specifically for the verification of the EPA Region 3 

SOP. The QAPP was approved on April 4, 2012. Since then, two surveillance audits and two internal 

TSAs have been performed, specifically looking at procedures related to glycol standard 

preparation and analysis. The two surveillance audits resulted in one case of potentially mislabeled 

samples during stock solution preparation. The potential mislabeling was already identified and 

documented by the researchers involved and corrective action taken. The designated EPA QA 

Manager found the methods in use satisfactory and further recommendations for improving the QA 

process were unnecessary. The internal TSAs also yielded no acts, errors, or omissions that would 

have a significant adverse impact on the quality of the final product. 

70 Major and trace elements are identified in the retrospective case study QAPPs found at 


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6. Toxicity Assessment 

Throughout the hydraulic fracturing water lifecycle, routes exist through which fracturing fluids 

and/or naturally occurring substances could be introduced into drinking water resources. To 

support future risk assessments, the EPA is gathering existing data regarding toxicity and potential 

human health effects associated with the chemicals reported to be in fracturing fluids and found in 

wastewater. At this time, the EPA has not made any judgment about the extent of exposure to these 

chemicals when used in hydraulic fracturing fluids or found in hydraulic fracturing wastewater, or 

their potential impacts on drinking water resources. 

6.1. Relationship to the Hydraulic Fracturing Study 

The EPA is compiling existing information on chemical, physical, and toxicological properties of 

hydraulic fracturing-related chemicals, which include chemicals reported to be used in injected 

hydraulic fracturing fluids and chemicals detected in flowback and produced water. There are 

currently over 1,000 chemicals. This work focuses particularly on compiling and evaluating existing 

toxicological properties and will inform answers to the research questions listed in Table 47. 

Table 47. Secondary research questions addressed by compiling existing information on hydraulic fracturing-related 

chemicals. 





What are the chemical, physical, and toxicological properties of 

hydraulic fracturing chemical additives 

What are the chemical, physical, and toxicological properties of 

hydraulic fracturing wastewater constituents 

6.2. Project Introduction 

Given the potential for accidental human exposure due to spills, improper wastewater treatment, 

and potential seepage, it is important to understand the known and potential hazards posed by the 

diversity of chemicals needed during hydraulic fracturing. The US House of Representatives’ 

Committee on Energy and Commerce Minority Staff released a report (2011) noting that more than 

650 products (i.e., chemical mixtures) used in hydraulic fracturing contain 29 chemicals that are 

either known or possible human carcinogens or are currently regulated under the SDWA (see Table 

11 in Section 3.1) (USHR, 2011). However, the report did not characterize the inherent chemical 

properties and potential toxicity of many of the reported compounds. The identification of inherent 

chemical properties will facilitate the development of models to predict environmental fate, 

transport, and the toxicological properties of chemicals. Through this level of understanding, 

scientists can design or identify more sustainable alternative chemicals that minimize or even avoid 

many fate, transport, and toxicity issues, while maintaining or improving commercial use. 

The EPA must understand (1) potential hazards inherent to the chemicals being used in or released 

by hydraulic fracturing and returning to the surface in flowback and produced water, (2) doseresponse 

characteristics, and (3) potential exposure levels in order to assess the potential impacts 

to human health from ingestion of drinking water that might contain the chemicals. The 

information from the toxicity assessment project provides a foundation for future risk assessments. 

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While the EPA currently does not have plans to conduct a formal risk assessment on this topic, the 

information may aid others who are investigating the risk of exposure. 

6.3. Research Approach 

Once the EPA identifies chemicals reported to be used in hydraulic fracturing fluids or found in 

flowback and produced water, physicochemical properties and chemical structures are assigned 

using various chemical software packages. Toxicological properties are then identified from 

authoritative sources or are estimated based on chemical structure. 

Identification of Chemicals. The EPA, to date, has identified nine sources, listed in Table 48, that 

contain authoritative information on chemicals in used in hydraulic fracturing fluids or found in 

hydraulic fracturing wastewater. The sources have been used to compile two lists: chemicals 

reported to be used in hydraulic fracturing fluids and chemicals detected in hydraulic fracturing 

wastewater. Chemicals will be added to the two lists as new data become available. 

Table 48. References used to develop a consolidated list of chemicals reportedly used in hydraulic fracturing fluids 

and/or found in flowback and produced water. 

Description / Content 

Chemicals reportedly used by 14 hydraulic fracturing service 

companies from 2005 to 2009 

Products and chemicals used during natural gas operations 

with some potential health effects 

Chemicals used or proposed for use in hydraulic fracturing 

and chemicals found in flowback 

Chemicals reportedly used by nine hydraulic fracturing service 

companies from 2005 to 2010 

MSDSs provided to the EPA during on-site visits 

Table 4-1: Characteristics of undiluted chemicals found in 

hydraulic fracturing fluids (based on MSDSs) 

Chemicals used in Pennsylvania for hydraulic fracturing 

activities (compiled from MSDSs) 

Chemical records entered in FracFocus for individual wells 

from January 1, 2011, through February 27, 2012 

Chemicals detected in flowback from 19 hydraulically 

fractured shale gas wells in Pennsylvania and West Virginia 

Chemicals reportedly detected in flowback and produced 

water from 81 wells 

Reference 

USHR, 2011 

Colborn et al., 2011 

NYSDEC, 2011 

US EPA, 2011b 

Material Safety Data Sheets 

US EPA, 2004b 

PADEP, 2010 

GWPC, 2012b 

Hayes, 2009 

US EPA, 2011k 

While compiling the list of chemicals used in fracturing fluids, the EPA identified instances where 

various chemical names were reported for a single CASRN. Chemical name and structure 

annotation QC methods were applied to the reported chemicals in order to standardize the 

chemical names; this process is described in “Chemical Information Quality Review Procedures” for 

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the Distributed Structure-Searchable Toxicity (DSSTox) Database Network. 71 The chemical QC 

methods included ensuring correct chemical names and CASRNs, and eliminating duplicates where 

appropriate. Chemical structures from the DSSTox database were assigned where possible. 

Physicochemical Properties. Physicochemical properties of chemicals in the hydraulic fracturing 

fluid chemical list were generated from the two-dimensional (2-D) chemical structures from the 

EPA’s DSSTox Database Network in structure-data file format. Properties were calculated using 

LeadScope chemoinformatic software (Leadscope Inc., 2012), Estimation Programs Interface Suite 

for Microsoft Windows (US EPA, 2012a), and QikProp (Schrodinger, 2012). 72 Both Leadscope and 

Qikprop software require input of desalted structures. Therefore, the structures were desalted, a 

process where salts and complexes are simplified to the neutral, uncomplexed form of the chemical, 

using Desalt Batch option in ChemFolder (ACD Labs, 2008). All Leadscope general chemical 

descriptors (Parent Molecular Weight, AlogP, Hydrogen Bond Acceptors, Hydrogen Bond Donors, 

Lipinski Score, Molecular Weight, Parent Atom Acount, Polar Surface Area, and Rotatable Bonds) 

were calculated by default. For EPISuite properties, both the desalted and non-desalted 2-D files 

were run using Batch Mode to calculate environmentally relevant, chemical property descriptors. 

The chemical descriptors in QikProp require 3-D chemical structures. For these calculations, the 2 

D desalted chemical structures were converted to 3-D using the Rebuild3D function in the 

Molecular Operating Environment software (Chemical Computing Group). All computed 

physicochemical properties are added into the structure-data file prior to assigning toxicological 

properties. 

Toxicological Properties. Known and predicted toxicity reference values are being combined into a 

single toxicity reference value resource for hydraulic fracturing-related chemicals. The EPA’s list of 

hydraulic fracturing-related chemicals was cross-referenced against the following nine sources to 

obtain authoritative toxicity reference values: 

• US EPA Integrated Risk Information System (IRIS) 

• US EPA Provisional Peer-Reviewed Toxicity Value (PPRTV) database 

• US EPA Health Effects Assessment Summary Tables 

• Agency for Toxic Substances and Disease Registry Minimum Risk Levels 

• State of California Toxicity Criteria Database 

• State of Alabama Risk-Based Corrective Action document 

• State of Florida Cleanup Target Levels 

• State of Hawaii Maximum Contaminant List 

• State of Texas Effects Screening Levels List 

71 For more information on DSSTox, see http://www.epa.gov/ncct/dsstox/ChemicalInfQAProcedures.html. 

72 The QikProp, EPI Suite, and LeadScope chemoinformatics programs calculate complementary properties with some 

overlap due to the process being performed in batch mode with all default properties included. 

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Authoritative toxicity reference values have been identified for over 100 of the more than 1,000 

chemicals reported as being present in injected water or present in produced water. These include 

the benzene, toluene, ethylbenzene, and xylene (BTEX) chemicals, and over 70 others with toxicity 

reference values in the IRIS and PPRTV databases. 

For the remaining chemicals that lack authoritative toxicity reference values, the structure-data file 

(generated for assigning physicochemical properties) can be used with the quantitative structure 

toxicity relationship software Toxicity Prediction by Komputer Assisted Technology, or TOPKAT 

(Accelrys Discovery Studio, 2012) to identify toxicity values. Rat chronic lowest observed adverse 

effect levels (LOAELs) were estimated using the LOAEL module for TOPKAT. The LOAEL module 

compares LOAEL values from open literature, National Cancer Institute/National Toxicology 

Program technical reports, and EPA databases to estimated rat oral LD 50 values, and then compares 

the octanol-water partition coefficient from the chemical structure data file to the range in the 

training set. 

The estimated LOAEL values will be compared to the authoritative toxicity reference values (for the 

chemicals with these authoritative values) to provide an estimate of how similar these values are. It 

is important to note that there may be significant deviation between the estimated LOAEL and the 

authoritative toxicity reference value for any given chemical due to the use of uncertainty factors in 

calculating the reference value, the fact that the reference values are not based on a rat chronic 

assay, and whether the reference values are calculated using the benchmark dose, a no observed 

adverse effect level, or a LOAEL. However, there is evidence that the estimated LOAEL is generally 

within 100 times the concentration of the actual rat chronic LOAEL (Rupp et al., 2010). 

6.4. Status and Preliminary Data 

Chemicals used in fracturing fluids or found in flowback and produced water, reported by the 

sources listed in Table 48, were consolidated and annotated, resulting in lists containing 1,027 

unique chemical substances, of which 751 could be assigned a chemical structure and all but 5 

assigned CASRNs. Physicochemical properties have been obtained for 318 of the 751 chemicals 

with structures. Physicochemical properties for the remainder of the chemicals with structures are 

currently being calculated. There were an additional 409 substances that were too poorly defined 

in the original lists to be unambiguously designated as unique substances, assigned CASRNs or 

chemical structures. The chemical lists are provided in Appendix A. The EPA has completed the first 

phase of development for the toxicity reference value database described above. 

6.5. Next Steps 

The EPA is currently identifying any additional state-based reference value data sources that can be 

useful; these additional sources, if any, will be brought into the database as they are identified. 

6.6. Quality Assurance Summary 

There are two QAPPs associated with this project. The first “Health and Toxicity Theme Hydraulic 

Fracturing Study Immediate Office National Center for Environmental Assessment,” was approved 

February 2012 and describes the development of the toxicity reference value master spreadsheet 

(US EPA, 2012k). The second QAPP, “Health and Toxicity (HT) Hydraulic Fracturing (HF) National 

Center for Computational Toxicology,” was approved February 2012 and describes the planning 

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and quality processes for the generation of the chemical lists and the calculation of physicochemical 

properties for the chemicals for which chemical structures can be assigned (US EPA, 2012i). 

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7. Case Studies 

7.1. Introduction to Case Studies 

Case studies are widely used to conduct in-depth investigations of complex topics and provide a 

systematic framework for investigating relationships among relevant factors. In conjunction with 

other elements of the research program, they help determine whether hydraulic fracturing can 

impact drinking water resources and, if so, the extent and possible causes of any impacts. Case 

studies may also provide opportunities to assess the fate and transport of fluids and contaminants 

in different regions and geologic settings. Results from the case studies are expected to help answer 

the secondary research questions listed in Table 49. 

Table 49. Secondary research questions addressed by conducting case studies. 





Applicable Secondary Research Questions 

• If spills occur, how might hydraulic fracturing chemical additives 


• How effective are current well construction practices at containing 

gases and fluids before, during, and after hydraulic fracturing 

• Can subsurface migration of fluids or gases to drinking water 

resources occur, and what local geologic or man-made features 

might allow this 

• If spills occur, how might hydraulic fracturing wastewaters 


Two types of case studies are being conducted as part of this study. Retrospective case studies focus 

on investigating reported instances of drinking water resource contamination in areas where 

hydraulic fracturing events have already occurred. Prospective case studies involve sites where 

hydraulic fracturing will be implemented after the research begins, which allows sampling and 

characterization of the site before, during, and after drilling, injection of the fracturing fluid, 

flowback, and production. The EPA continues to work with industry partners to design and develop 

prospective case studies. Because prospective case studies remain in their early stages, the 

progress report focuses on the progress of retrospective case studies only. 

To select the retrospective case study sites, the EPA invited stakeholders from across the country to 

participate in the identification of locations for potential case studies through informational public 

meetings and the submission of electronic or written comments. Following thousands of comments, 

over 40 locations were nominated for inclusion in the study. 73 These locations were prioritized and 

chosen based on a rigorous set of criteria, including proximity of population and drinking water 

supplies, evidence of impaired water quality, health and environmental concerns, and knowledge 

gaps that could be filled by a case study at each potential location. Sites were prioritized based on 

geographic and geologic diversity, population at risk, geologic and hydrologic features, 

characteristics of water resources, and land use (US EPA, 2011e). Five retrospective case study 

locations were ultimately chosen for inclusion in this study and are shown in Figure 27. 

73 A list of the sites submitted for consideration can be found in the Study Plan. 

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Figure 27. Locations of the five retrospective case studies chosen for inclusion in the EPA’s Study of the Potential 

Impacts of Hydraulic Fracturing on Drinking Water Resources. The locations were nominated by stakeholders and 

selected based on criteria described in the text. (ESRI, 2010a, b; US EIA, 2011d, e) 

7.1.1. General Research Approach 

Although each retrospective case study differs in the geologic and hydrologic characteristics, as well 

as the hydraulic fracturing techniques used and the oil and gas exploration and production history 

of the area, the methods used to assess potential drinking water impacts are applicable to all of the 

study sites. By coordinating the case study methods and analyses, it will be possible to compare the 

results of each study. Table 50 describes the general research approach being used for the 

retrospective case studies. 74 The tiered scheme uses the results of earlier tiers to refine sampling 

activities in later tiers. This approach is both useful and appropriate when the impacts to drinking 

water resources and the potential sources of the impacts are unknown. For example, it allows the 

sampling to verify key findings and adjust to the improved understanding of the site. 

74 The Dunn County, North Dakota, retrospective case study does not use this tiered sampling plan because it is designed 

to examine the impacts of a well blowout during hydraulic fracturing. Since the potential source of contamination is 

known, the tiered sampling plan is not necessary. 

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Table 50. General approach for conducting retrospective case studies. The tiered approach uses the results of earlier 

tiers to refine sampling activities in later tiers. 

Tier Goal Critical Path 

• Evaluate existing data and information from operators, private 

citizens, state and local agencies, and tribes (if any) 

1 Verify potential issue 

• Conduct site visits 

• Interview stakeholders and interested parties 

2 

3 

4 

Determine approach 

for detailed 

investigations 

Conduct detailed 

investigations to 

detect and evaluate 

potential sources of 

contamination 

Determine the 

source(s) of any 

impacts to drinking 

water resources 

• Conduct initial sampling of water wells, taps, surface water, and 

soils 

• Identify potential evidence of drinking water contamination 

• Develop conceptual site model describing possible sources and 

pathways of the reported or potential contamination 

• Develop, calibrate, and test fate and transport model(s) 

• Conduct additional sampling of soils, aquifer, surface water, and 

wastewater pits/tanks (if present) 

• Conduct additional testing, including further water testing with new 

monitoring points, soil gas surveys, geophysical testing, well 

mechanical integrity testing, and stable isotope analyses 

• Refine conceptual site model and further test exposure scenarios 

• Refine fate and transport model(s) based on new data 

• Develop multiple lines of evidence to determine the source(s) of 

impacts to drinking water resources 

• Exclude possible sources and pathways of the reported 

contamination 

• Assess uncertainties associated with conclusions regarding the 

source(s) of impacts 

Each retrospective case study has developed a QAPP that describes the detailed plan for the 

research at that location. The QAPP integrates the technical and quality aspects of the case study in 

order to provide a guide for obtaining the type and quality of environmental data required for the 

research. Before each new tier of sampling begins, the QAPPs are revised to account for any 

changes. 

Ground water samples have been collected at all retrospective case study locations. The samples 

come from a variety of available sources, such as existing monitoring wells, domestic and municipal 

water wells, and springs. Surface water, if present, has also been sampled. During sample collection, 

the following water quality parameters were monitored and recorded: 

• Temperature 

• pH 

• TDS 

• Specific conductivity 

• Alkalinity 

• Turbidity 

• Dissolved oxygen 

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• Oxidation/reduction potential 

• Ferrous iron 

• Hydrogen sulfide 

Each water sample has been analyzed for a suite of chemicals; groups of analytes and examples of 

specific chemicals of interest are listed in Table 51. These chemicals include major anions, 

components of hydraulic fracturing fluids (i.e., glycols), and potentially mobilized natural occurring 

substances (i.e., metals); 75 these chemicals are thought to be present frequently in hydraulic 

fracturing fluids or wastewater. As indicated in Table 51, stable isotope analyses are also being 

conducted. Stable isotope compositions can be important indicators of what is naturally occurring 

in the environment being studied. If an element has multiple stable isotopes, one is usually the most 

common form in that environment. Due to different processes that may occur in or around the 

environment, other stable isotopes of the element may be found. The different isotopes can make it 

easier to determine the source of, or distinguish between, sources of contamination. 

Table 51. Analyte groupings and examples of chemicals measured in water samples collected at the retrospective 

case study locations. 

Analyte Groups 

Examples 

Anions 

Bromide, chloride, sulfate 

Carbon group Dissolved organic carbon,* dissolved inorganic carbon † 

Dissolved gases 

Methane, ethane, propane 

Extractable petroleum hydrocarbons Gasoline range organics, § diesel range organics ‡ 

Glycols 

Diethylene glycol, triethylene glycol, tetraethylene glycol 

Isotopes 

Isotopes of oxygen and hydrogen in water, carbon and 

hydrogen in methane, strontium 

Low molecular weight acids 

Formate, acetate, butyrate 

Measures of radioactivity 

Radium, gross α, gross β 

Metals 

Arsenic, manganese, iron 

Semivolatile organic compounds Benzoic acid; 1,2,4-trichlorobenzene; 4-nitrophenol 

Surfactants 

Octylphenol ethoxylate, nonylphenol 

Volatile organic compounds 

Benzene, toluene, styrene 

* Dissolved organic carbon is a result of the decomposition of organic material in aquatic systems. 

† 

Dissolved inorganic carbon is the sum of the carbonate species (e.g., carbonate, bicarbonate) dissolved in water. 

§ 

Gasoline range organics include hydrocarbon molecules containing 5–12 carbon atoms. 

‡ 

Diesel range organics include hydrocarbon molecules containing 15–18 carbon atoms. 

The samples taken for the case studies were analyzed by the EPA Region 8 Laboratory and the EPA 

Robert S. Kerr Environmental Research Center. A laboratory TSA was conducted at the EPA Region 

8 Laboratory on July 26, 2011; no findings were identified. In addition, a laboratory TSA was 

conducted for the onsite analytical support at the Robert S. Kerr Environmental Research Center on 

July 28, 2011, which included Shaw Environmental and the EPA General Parameter Lab; no findings 

75 A complete list of chemicals and corresponding analytical methods is available in the QAPPs for each case study. See 


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were identified. The laboratory TSAs were conducted on these laboratories during the first 

retrospective case study sampling event to identify any problems early and allow for corrective 

actions, if needed. Additional TSAs will be performed if determined to be necessary based on 

quality concerns. 

This chapter includes progress reports for the following retrospective case studies: 

7.2. Las Animas and Huerfano Counties, Colorado ....................................................................................... 131 

Investigation of potential drinking water impacts from coalbed methane extraction in the 

Raton Basin 

7.3. Dunn County, North Dakota ........................................................................................................................... 137 

Investigation of potential drinking water impacts from a well blowout during hydraulic 

fracturing for oil in the Bakken Shale 

7.4. Bradford County, Pennsylvania .................................................................................................................... 142 

Investigation of potential drinking water impacts from shale gas development in the Marcellus 

Shale 

7.5. Washington County, Pennsylvania.............................................................................................................. 148 

Investigation of potential drinking water impacts from shale gas development in the Marcellus 

Shale 

7.6. Wise County, Texas ............................................................................................................................................ 153 

Investigation of potential drinking water impacts from shale gas development in the Barnett 

Shale 

7.2. Las Animas and Huerfano Counties, Colorado 


Las Animas and Huerfano Counties, Colorado, are located on the eastern edge of the Rocky 

Mountains and have a combined population of about 22,000 people and a population density of 

about 4 people per square mile (USCB, 2010c, d). As shown in Figure 28, the coal-bearing region of 

the Raton Basin occupies an area of 1,100 square miles within these two counties. The development 

of CBM resources in the Raton and Vermejo Formations within the Raton Basin has increased due 

to advances in hydraulic fracturing technology (Keighin, 1995; Watts, 2006b). 

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Figure 28. Extent of the Raton Basin in southeastern Colorado and northeastern New Mexico (ESRI, 2012; US EIA, 

2011d; USCB, 2012a, b, c). The case study includes two locations: “North Fork Ranch,” located northwest of the city 

of Trinidad in western Las Animas County, and “Little Creek,” located southwest of the city of Walsenburg in 

Huerfano County. 

Study site locations in Las Animas and Huerfano Counties were selected in response to ongoing 

complaints 

about changes 

in appearance, odor, and taste associated with drinking water in 

domestic wells. 

These 

sites include “North Fork 

Ranch,” located 

northwest of the city 

of Trinidad in 

western 

Las Animas County, and 

“Little Creek,” 

located 

southwest 

of the 

city of 

Walsenburg 

in 

Huerfano 

County. In some 

locations, 

point-of-use water treatment systems have been 

installed 

on 

properties to treat elevated methane and sulfide concentrations in well water. This case 

study 

focuses on 

the potential 

impacts of 

hydraulic fracturing on 

drinking 

water resources near 

these 

two 

study sites. 

Potential 

sources 

of ground 

water contamination 

under consideration 

include 

activities 

associated with natural sources, CBM extraction 

( such 

as leaking or 

abandoned 

pits) 

, gas 

well 

completion 

and 

enhancement techniques, improperly 

plugged 

and 

abandoned 

wells, gas 

migration, 

and residential impacts. 

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7.2.2. Site Background 

Geology. The Raton Basin is a north-south trending sedimentary and structural depression located 

along the eastern edge of the Rocky Mountains, between the Sangre de Cristo Mountains to the west 

and the Apishapa, Las Animas, and Sierra Grande arches on the east (Watts, 2006a). This chevronshaped 

basin encompasses roughly 2,200 square miles of southeastern Colorado and northeastern 

New Mexico, extending from southern Colfax County, New Mexico, through Las Animas County, 

Colorado, and northward into Huerfano County, Colorado, as shown in Figure 28 (Tremain, 1980). 

It is the southernmost of the several major coal-bearing basins located along the eastern margin of 

the Rocky Mountains (Johnson and Finn, 2001). Within the Raton Basin, the Vermejo and Raton 

Formations contain CBM resources being extracted using hydraulic fracturing. 

Las Animas and Huerfano Counties are underlain by sedimentary bedrock ranging in age from the 

late Cretaceous to the Eocene (see Appendix D for a geologic timeline). Igneous intrusions, dating to 

the Eocene, Miocene, and Pliocene epochs, occur throughout the area. The sedimentary sequence 

exposed within the Raton Basin was deposited in association with regression of the Cretaceous 

Interior Seaway, and the stratigraphy reflects deposition in fluvial systems and peat-forming 

swamps (Cooper et al., 2007; Flores, 1993). Numerous discontinuous and thin coalbeds are located 

in the Vermejo and Raton Formations, which lie directly above the Trinidad Sandstone. The upper 

Trinidad intertongues with, and is overlain by, the coal-bearing Vermejo Formation (Topper et al., 

2011). No coal is found below this sandstone (Greg Lewicki & Associates, 2001). 

Individual coalbeds in the Vermejo Formation consist of interbedded shales, sandstones, and 

coalbeds. The Vermejo Formation ranges in thickness from 150 feet in the southern part of the 

basin to 410 feet in the northern part (Greg Lewicki & Associates, 2001). This formation contains 

from 3 to 14 coalbeds over 14 inches thick throughout the entire basin, and total coal thickness 

typically ranges from 5 to 35 feet (US EPA, 2004b). 

The Raton Formation overlies the Vermejo Formation. The Raton Formation ranges from 0 to 2,100 

feet thick and is composed of a basal conglomerate, a middle coal-bearing zone, and an upper 

transitional zone (Johnson and Finn, 2001; US EPA, 2004b). Its middle coal-bearing zone is 

approximately 1,000 feet thick and consists of shales, sandstones, and coalbeds (Greg Lewicki & 

Associates, 2001). This zone also contains coal seams that have been mined extensively; total coal 

thickness ranges from 10 feet to more than 140 feet in this zone, with individual seams ranging in 

thickness from several inches to more than 10 feet (US EPA, 2004b). Sandstones are interbedded 

with coalbeds that are currently being developed for CBM, and the coalbeds are the likely source for 

gas found in the sandstones (Johnson and Finn, 2001). 

Water Resources. Las Animas and Huerfano Counties are located in the Arkansas River Basin and 

are drained by the Purgatoire, Apishapa, and Cucharas Rivers. The coal-bearing region of the Raton 

Basin is predominantly drained by the Purgatoire and Apishapa Rivers; many stream segments of 

these rivers are currently on Colorado’s list of impaired waters (CDPHE, 2012). Annual 

precipitation in the Raton Basin is generally correlated to elevation, ranging from over 30 inches 

per year in the Spanish Peaks to less than 16 inches per year in eastern portions of the basin, which 

are at lower elevation. Much of the precipitation falls as winter snow in the mountains or as intense 

summer rain in the plains (Abbott, 1985; S.S. Papadopulos & Associates Inc, 2008). Ground water 

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based drinking water resources in Las Animas and Huerfano Counties reside in four bedrock 

aquifers: (1) the Dakota Sandstone and Purgatoire Formation; (2) the Raton Formation, Vermejo 

Formation, and Trinidad Sandstone; (3) the Cuchara-Poison Canyon Formation; and (4) volcanic 

rocks (Abbott et al., 1983). Sources of recharge to the aquifers include runoff from the Sangre de 

Cristo Mountains, precipitation infiltration, and infiltration from streams and lakes (Abbott et al., 

1983; CDM and GBSM, 2004). The depth to ground water depends mostly on topographic position. 

In all areas but the southeast corner of the basin, water can be encountered at less than 200 feet 

below ground surface (CDM and GBSM, 2004). Regional ground water flow is generally from west 

to east, except where it is intercepted by valleys that cut into the rock (Watts, 2006b). 

Within the hydrogeologic units of the Raton Basin, sandstone and conglomerate layers transmit 

most of the water; shale and coal layers generally retard flow. However, fracture networks in the 

shales and coal provide pathways which can transmit fluids or gas. Talus and alluvium may yield 

large quantities of water, but are limited in size, and discharges from these units fluctuate 

seasonally (Abbott et al., 1983). Aquifer tests in the Raton-Vermejo aquifers indicate hydraulic 

conductivities that range from 0 to 45 feet per day (Abbott et al., 1983). 

Geologic formations have distinctive ground water chemistry. The Cuchara-Poison Canyon 

Formation is typically calcium-bicarbonate type with less than 500 milligrams per liter TDS 

content, while the Raton-Vermejo-Trindad aquifer is typically sodium-bicarbonate with TDS 

concentrations less than 1,500 milligrams per liter. Abbott et al. (1983) note that concentrations of 

boron, fluoride, iron, manganese, mercury, nitrate, selenium, and zinc are locally elevated due to a 

variety of geologic processes and human activities. High concentrations of fluoride occur in the 

Poison Canyon and Raton Formations, possibly due to the dissolution of detrital fluorite. Iron and 

manganese concentrations may be also elevated, particularly in areas where coals are present, due 

to the dissolution of pyrite and/or siderite contained in the coal seams. Nitrate enrichment often 

occurs in alluvial aquifers where fertilizers or animal wastes add nitrogen (Abbott et al., 1983). 

Oil and Gas Exploration and Production. The Raton Basin contains substantial amounts of high- and 

medium-volatile bituminous coals, which extend from outcrops along the periphery of the region to 

depths of at least 3,000 feet in the deepest parts of the region (Jurich and Adams, 1984). Most of 

these coal resources are in the Vermejo and Raton Formations, which are the target formations for 

CBM production (Macartney, 2011; Tyler, 1995). These coalbeds have been extensively mined in 

the peripheral outcrop belt along major stream valleys, as well as in a few structural uplifts within 

the interior of the basin (Dolly and Meissner, 1977). Total coal resources estimated in the basin 

range from 1.5 billion to more than 17 billion short tons (Flores and Bader, 1999). 

Production of natural gas in the Raton Basin began in the 1980s, but before 1995, there were no gas 

distribution lines out of the basin and fewer than 60 wells had been drilled (S.S. Papadopulos & 

Associates Inc, 2008). The Raton Basin is estimated to contain as much as 18.4 trillion cubic feet of 

CBM (Tyler, 1995). This area has recently seen a rapid expansion in the production of natural gas 

with recent advances in hydraulic fracturing technology. Between 1999 and 2004, annual 

production of Raton Basin CBM in Las Animas and Huerfano Counties increased from about 28 

billion cubic feet to about 80 billion cubic feet, and the number of producing wells grew from 478 

wells to 1,543 wells. During the same period, annual ground water withdrawals for CBM production 

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increased from about 1.45 billion gallons to about 3.64 billion gallons (Watts, 2006b). Expansion of 

CBM wells has focused on the development of the Vermejo coals, since these coals are thicker and 

more continuous than those located in the Raton Formation (US EPA, 2004b). 


A detailed description of the sampling methods and procedures for this case study can be found in 

the project’s QAPP (US EPA, 2012o). Ground water and surface water sampling in this area is 

intended to provide a survey of water quality in Las Animas and Huerfano Counties. Data collection 

involves sampling water from domestic wells, surface water bodies (streams), monitoring wells, 76 

and gas production wells at locations in both Las Animas and Huerfano Counties, as indicated in 

Figure 29. The locations of these sampling sites were chosen based on their proximity to production 

activity. 

Figure 29. Locations of sampling sites in Las Animas and Huerfano Counties, Colorado. Water samples have been 

taken from domestic wells, surface water bodies (streams), monitoring wells, and gas production wells. 

In addition to the analytes discussed in Section 7.1.1, the stable isotope compositions of carbon and 

hydrogen in methane, as well as the stable carbon isotope composition of dissolved inorganic 

carbon and the stable sulfur isotope composition of dissolved sulfate and dissolved sulfide, are 

76 Monitoring wells were installed by either Pioneer Natural Resources or Petroglyph Energy. 

135



being analyzed as part of this case study. Microbial analyses are also being conducted on water 

samples collected at this case study location in order to better understand the biogeochemical 

cycling of carbon and sulfur in ground water. Together, these measurements support the objective 

of determining if ground water resources have been impacted, and, if so, whether they were 

impacted by hydraulic fracturing activities or other sources of contamination. 


As of August 2012, two sampling trips have been conducted: one in October 2011 and another in 

May 2012. During the October 2011 sampling trip, two production wells, five monitoring wells, 14 

domestic water wells, and one surface water location were sampled. During the May 2012 sampling 

trip, two production wells, three monitoring wells, 12 domestic water wells, and three surface 

water locations were sampled. The locations of sampling sites are displayed in Figure 29. 


Additional fieldwork to collect ground and surface water at each sampling location is tentatively 

scheduled for late 2012 and spring 2013. Sampling locations and analytes measured may be refined 

based on the results of the first two sets of samples. More focused investigations will also be 

conducted, if warranted, at locations where potential impacts associated with hydraulic fracturing 

may have occurred. 


The initial QAPP for this case study, “Hydraulic Fracturing Retrospective Case Study, Raton Basin, 

CO,” was approved by the designated EPA QA Manager on September 20, 2011 (US EPA, 2012o). A 

revision to the QAPP was made before the second sampling event and was approved on April 30, 

2012, to update project organization, update lab accreditation information, update sampling 

methodology, add sulfur isotope analyses, modify critical analytes, and change the analytical 

method for determining hydrogen and oxygen stable isotope ratios in water . There have been no 

significant deviations from the QAPP during any sampling event, and therefore no impact on data 

quality. A field TSA was conducted on October 4, 2011, during the first sample collection event; no 

findings were identified. See Section 7.1.1 for information related to the laboratory TSAs. 

As results are reported and raw data are provided from the laboratories, ADQs are performed to 


qualified, if necessary, based on these ADQs. The results of these ADQs will be reported in the final 

report on this project. 

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7.3. Dunn County, North Dakota 


Dunn County, North Dakota, is a rural county with a population of 3,500 and an average population 

density of 1.8 people per square mile (USCB, 2010b); Killdeer is its largest city. This part of North 

Dakota is currently experiencing renewed natural gas exploration and a boom in oil production 

from the Bakken Shale, which extends domestically from western North Dakota to parts of 

northeastern Montana (Figure 30). The area’s increased oil and gas exploration has relied greatly 

upon both horizontal drilling and hydraulic fracturing technologies. 

Figure 30. Extent of the Bakken Shale in North Dakota and Montana (US EIA, 2011d; USCB, 2012a, c). The case 

study focuses on a well blowout that occurred in Dunn County, North Dakota, in September 2010. 

The EPA’s case study site in Killdeer, North Dakota, was chosen at the request of the state to 

specifically examine any water resource impacts from a well blowout in September 2010 that 

resulted in an uncontrolled release of hydraulic fracturing fluids and formation fluids. The Killdeer 

Aquifer, the main source of drinking water for the city of Killdeer, underlies the study site. The 

137



blowout occurred at the Franchuk 44-20 SWH well, which is just outside the Killdeer municipal 

water supply well’s 2.5 mile wellhead protection zone. 

The uncontrolled blowout occurred on September 1, 2010, during the fifth stage of a hydraulic 

fracturing treatment of the Franchuk 44-20 SWH well. The intermediate well casing burst because 

of a 8,390 pounds per square inch pressure spike that released the pop-off relief valve. Hydraulic 

fracturing fluids and formation fluids began flowing from the ground around the well at several 

points and then flowed toward the northeast corner of the well pad, where they were contained by 

a 2 foot berm. During that day, 47,544 gallons of fluids were removed from the site. The following 

day, 88,000 gallons of fluids were removed from the site, and 15,120 gallons of mud were circulated 

into the well to kill it. Three monitoring wells were installed, but not sampled. Two down-gradient 

homeowner wells, an up-gradient homeowner well, and two municipal water wells were sampled 

on September 2. Three cement plugs were installed beginning at 9,000 feet in the wellbore, and 

105,252 gallons of fluid were removed from the site. A bridge plug was set at 9,969 feet on 

September 6. From September 30 to October 15, 2,000 tons of contaminated soil were removed and 

disposed of (Jacob, 2011). Since the blowout, the State of North Dakota has overseen site cleanup 

and has required the well’s operator to conduct ground water monitoring on a quarterly basis. In 

November 2010, the state asked the EPA to consider this site as part of this study, and the EPA 

agreed to do so. 


Geology. Dunn County is located in west-central North Dakota and is underlain by the sedimentary 

rocks of the Williston Basin. Although Dunn County marks the southern extent of glaciations in 

North Dakota, most of the glacial deposits have been eroded and the surface sediments are 

characterized by post-glacial, channel-fill deposits (Murphy, 2001). As described in Nordeng 

(2010), the Bakken formation is primarily composed of shale and dolomite, with some sandstone 

and siltstone. The Bakken Shale is of Late Devionian-Early Mississippian age (Appendix D) and is an 

organic-rich marine shale. It has no surface outcrop and is constrained by the Madison Formation 

above and the Wabamum, Big Valley, and Torquary Formations below (Murphy, 2001; Nordeng, 

2010). The depths to the Bakken Shale range from 9,500 to 10,500 feet and its thickness ranges 

from very thin up to 140 feet (Carlson, 1985; Murphy, 2001). 

Water Resources. Dunn County is a semi-arid region. Surface water in Dunn County is in the 

Missouri River Basin and includes the Little Missouri River to the northwest of the county and Lake 

Sakakawea to the northeast. These water resources supply water for domestic use, irrigation, 

industrial water, and hydraulic fracturing. 

One of the major sources of drinking water in Killdeer is the Killdeer Aquifer: a glacial outwash 

aquifer, composed of fine to medium sand with course gravel near its base. It is shallow, with a 

maximum thickness of 233 feet. The aquifer is generally overlain by clay and silt soils (Klausing, 

1979). Yields from the Killdeer Aquifer are high, ranging from 50 to 1,000 gallons per minute 

(Klausing, 1979). The major water types in the Killdeer Aquifer are sodium bicarbonate and sodium 

sulfate. Table 52 shows background water quality data for the Killdeer Aquifer, compiled by 

Klausing (1979). 

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Table 52. Background water quality data for the Killdeer Aquifer in North Dakota (Klausing, 1979). The range of 

boron, chloride, and iron in some samples was below the detection limit (BDL). 

Parameter 

Bicarbonate 

Boron 

Chloride 

Fluoride 

Iron 

Nitrate 

Sodium 

Sulfate 

TDS 

Concentration Range 


374–1,250 

BDL–3.70 

BDL–25 

0.1–2 

BDL–5.50 

0.3–6.7 

50–1,350 

333–3,000 

234–5,030 

Mean Concentration 


713 

0.53 

4.5 

0.66 

1.03 

1.2 

413 

626 

1,531 

Oil and Gas Exploration and Production. Although it was known to contain large volumes of oil as 

early as the 1950s, difficulties in extracting the oil from the Bakken Shale kept production rates low 

(NDIC, 2012a). Hydraulic fracturing and horizontal drilling technologies have created greater 

access to the Bakken Shale oil reserves. In January 2003, Dunn County had 99 wells, producing 

approximately 86,000 barrels of oil (NDIC, 2003). By July 2012, the county had 854 wells, 

producing approximately 3.2 million barrels of oil (NDIC, 2012b). 


A detailed description of this case study’s sampling methods and procedures can be found in the 

QAPP (US EPA, 2011i). The primary objective of this case study is to assess the impacts of the 

Franchuk 44-20 SWH well blowout that occurred on September 1, 2010. Unlike the EPA’s other four 

retrospective case studies, the Killdeer case study does not use a tiered approach because the 

potential source of contamination is known. Ground water sampling includes domestic, municipal, 

water supply, and monitoring wells. 77 Figure 31 shows the sampling locations in Dunn County, 

North Dakota. 

77 Terracon Consultants was contracted by the well operator, Denbury Resources, for the installation of monitoring wells. 

139



Figure 31. Location of sampling sites in Dunn County, North Dakota. 

Domestic, municipal, and supply wells are being sampled at a tap as close to the wellhead as 

possible, before any treatment has occurred. Monitoring wells have been installed and have 

dedicated bladder pumps for sampling and purging operations. Water samples collected at these 

locations are being analyzed for the chemicals listed in Section 7.1.1 as well as the chemicals listed 

in the QAPP (US EPA, 2011i). The data collected as part of this case study will be compared to 

existing background data as part of the initial screening phase (Tier 2 in Table 50) to determine if 

any contamination has occurred in the study location. 


Two rounds of sampling were conducted in Killdeer in July and October 2011. Samples were 

collected at 10 monitoring wells, three domestic water wells, two water supply wells, and one 

municipal water well. The locations of sampling sites are displayed in Figure 31. 


At least one more round of sampling is planned to verify data collected from the first two rounds of 

sampling. Additional sampling locations or analytes may be included in future rounds as analytical 

data are evaluated and additional pertinent information becomes available. 

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The initial QAPP for this case study, “Hydraulic Fracturing Retrospective Case Study, Bakken Shale, 

Killdeer and Dunn County,” was approved by the designated EPA QA Manager on June 20, 2011 (US 

EPA, 2011i). A revision to the QAPP was made before the second sampling event and was approved 

on August 31, 2011, to address the collection of isotopic samples; revised sampling protocols for 

domestic, supply, and municipal wells; and analytical lab information. Another QAPP revision has 

been submitted for review by QA staff in preparation for the third sampling event. There have been 

no significant deviations from the QAPPs during earlier sampling events, and therefore no impact to 

data quality. A field TSA was conducted on July 19, 2011; no findings were identified. See Section 

7.1.1 for information related to the laboratory TSAs. 

As results are reported and raw data are provided from the laboratories, ADQs will be performed to 


qualified if necessary, based on these ADQs. The results of these ADQs will be reported in the final 


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7.4. Bradford County, Pennsylvania 

7. 4. 1. 

Project 

Introduction 

Bradford 

County is 

a rural 

county in northeastern Pennsylvania 

with an approximate total 

population 

of 63,000 

and 

an average population 

density of 55 

people per square mile 

( USCB, 

2010a). As shown in Figure 32, the Marcellus Shale underlies Bradford County, extending 

through 

much of New York, Pennsylvania, Ohio, and West Virginia. Recently, natural gas drilling in the 

Marcellus Shale has increased significantly in northeastern Pennsylvania, including Bradford 

County. 

Figure 32. Extent of the Marcellus Shale, which underlies large portions of New York, Ohio, Pennsylvania, and West 

Virginia ( US EIA, 2011d; USCB, 2012a, c). The case study focuses on reported changes in drinking water quality in 

Bradford County, Pennsylvania, with a few water samples taken in neighboring Susquehanna County. 

142



The EPA chose Bradford County, and parts of neighboring Susquehanna County, 78 as a retrospective 

case study location because of the extensive hydraulic fracturing activities occurring there, 

coincident with the large number of homeowner complaints regarding the appearance, odor, and 

possible health impacts associated with water from domestic wells. Additionally, the Pennsylvania 

Department of Environmental Protection has issued notices of violation for infractions at wells in 

this area, including a gas well blowout in Leroy Township of Bradford County in April 2011 that 

released a reported 10,000 gallons of flowback and produced water (SAIC Energy Environment & 

Infrastructure LLC and Groundwater & Environmental Services Inc., 2011). Initial sampling 

locations for this retrospective case study were chosen primarily based on individual homeowner 

complaints or concerns regarding potential adverse impacts to their well water from nearby 

hydraulic fracturing activities. If anomalies in ground water quality are found during sampling, all 

potential sources of contamination in the study area will be considered, including those not related 

to hydraulic fracturing. 


Geology. The geology of the study area has been extensively described in other studies and is 

summarized below (Carter and Harper, 2002; Milici and Swezey, 2006; Taylor, 1984; Williams et al., 

1998). The Bradford County study area is underlain by unconsolidated deposits of glacial and postglacial 

origin and the nearly flat-lying sedimentary bedrock of the Appalachian Basin. The glacial 

and post-glacial deposits consist of till, stratified drift, alluvium, and swamp deposits. The bedrock 

consists primarily of shale, siltstone, and sandstone of Devonian to Pennsylvanian age. The 

Devonian bedrock includes the Loch Haven and Catskill formations, both of which are important 

sources of drinking water in the study area. The Marcellus Shale, also known as the Marcellus 

Formation, is a Middle Devonian-age (Appendix D) shale with a black color, low density, and high 

organic carbon content. It occurs in the subsurface beneath much of Ohio, West Virginia, 

Pennsylvania, and New York (Figure 32). Smaller areas of Maryland, Kentucky, Tennessee, and 

Virginia are also underlain by the Marcellus Shale. In Bradford County, the Marcellus Shale 

generally lies 4,000 to 7,000 feet below the surface and ranges in thickness from 150 to 300 feet 

(Marcellus Center for Outreach and Research, 2012a, b). The Marcellus Shale is part of a 

transgressive sedimentary package, formed by the deposition of terrestrial and marine material in a 

shallow, inland sea. It is underlain by the sandstones and siltstones of the Onondaga Formation and 

overlain by the carbonate rocks of the Mahantango Formation. 

Within the Marcellus Shale, natural gas occurs within the pore spaces of the shale, within vertical 

fractures or joints of the shale, and adsorbed onto mineral grains and organic material. An 

assessment conducted by the USGS in 2011 suggested that the Marcellus Shale contains an 

estimated 84 trillion cubic feet of technically recoverable natural gas (Coleman et al., 2011). 

78 Four wells were sampled in Susquehanna County during the first round of sampling. Soon after, EPA Region 3 began an 

investigation of potential drinking water contamination in Dimock, located in Susquehanna County (see 

http://www.epa.gov/aboutepa/states/pa.html). In order to avoid duplication of effort, this case study focuses on 

reported changes in drinking water quality in Bradford County. Subsequent sampling for this case study has been, and 

will continue to be, done in Bradford County. 

143



Water Resources. The average precipitation in Bradford County is 33 inches per year. Summer 

storms produce about half of this precipitation; the remainder of the precipitation, and much of the 

ground water recharge, occurs during winter and spring (PADEP, 2012). Surface water in the study 

area is part of the Upper Susquehanna River Basin. The main branches of the Susquehanna River 

flow to the south, while the smaller tributaries are constrained by the northeast-southwest 

orientation of the Appalachian Mountains. Stratified drift aquifers and the Loch Haven and Catskill 

bedrock formations serve as primary ground water drinking sources in the study area. Glacial till is 

also tapped as a drinking water source at some locations (Williams et al., 1998). These resources 

provide water for domestic use, municipal water, manufacturing, irrigation, and hydraulic 

fracturing. 

The stratified drift aquifers in Bradford County occur as either confined or unconfined aquifers. The 

confined aquifers in the study area are composed of sand and gravel deposits of glacial, ice-contact 

origin and are typically buried by pro-glacial lake deposits; the unconfined aquifers are composed 

of sand and gravel deposited by glacial outwash or melt-waters. Depth to ground water varies 

throughout Bradford County and ranged from 1 to 300 feet for the wells sampled in the study. The 

median specific capacity of confined stratified drift aquifers is 11 gallons per minute per foot; the 

median specific capacity of unconfined stratified drift aquifers is 24 gallons per minute per foot 

(Williams et al., 1998). The specific capacity of wells completed in till or bedrock is typically 10 

times lower than in the stratified drift aquifers. 

Ground water in the study area is generally of two types: a calcium bicarbonate type in zones of 

unconfined flow and a sodium chloride type in zones of confined flow. Data from Williams et al. 

(1998) show that water wells completed in zones with more confined flow contain higher TDS 

(median concentration of 830 milligrams per liter), dissolved barium (median concentration of 2.0 

milligrams per liter), and dissolved chloride (median concentration of 349 milligrams per liter) 

compared to zones with unconfined flow. This is also true for concentrations of iron and manganese 

in the study area. Table 53 presents a summary of median and maximum concentrations of 

inorganic parameters in Bradford County ground water, based on the study conducted by Williams 

et al. (1998). 

Table 53. Background (pre-drill) water quality data for ground water wells in Bradford County, Pennsylvania (Williams 

et al., 1998). 

Parameter 

Median Concentration 


Pre - Drill Data 

Maximum Concentration 


Number of 

Samples 

Arsenic 0.009 0.072 16 

Barium 0.175 98 50 

Chloride 11 3,500 93 

Iron 0.320 15.9 95 

Manganese 0.120 1.03 77 

TDS 246 6,100 102 

pH (pH units) 7.25 8.8 102 

144



Naturally high levels of TDS, barium, and chloride found in ground water make it difficult to assess 

the potential impacts of hydraulic fracturing activities in this part of the country since these 

analytes would normally serve as indicators of potential impacts. In addition, methane occurs 

naturally in ground water in the study area, making an assessment of potential impacts of methane 

due to hydraulic fracturing on drinking water resources more challenging than at other study 

locations. 

Oil and Gas Exploration and Production. Gas drilling to depths of the Marcellus Shale and beyond 

dates back to the 1930s, although at that time, the Marcellus Shale was of little interest as a source 

of gas. Instead, gas was sought primarily from sandstone and limestone deposits, and the Marcellus 

Shale was only encountered during drilling to deeper targeted zones like the Oriskany Sandstone. 

Upon penetrating the Marcellus Shale, significant but generally short-lived gas flow would be 

observed. With the advent of modern hydraulic fracturing technology and the increasing price of 

gas, the Marcellus Shale has become an economical source of natural gas with the potential to 

produce several hundred trillion cubic feet (Milici and Swezey, 2006). In July 2008, there were only 

48 active permitted natural gas wells in Bradford County; by January 2012, there were 2,015 

(Bradford County Government, 2012). The wells are located throughout the county with an average 

density of actively permitted wells of 1.8 wells per square mile. 


Methods for sampling ground water and surface water are described in detail in the QAPP (US EPA, 

2012m). The primary objective of this case study is to determine if ground water resources have 

been impacted, and whether or not those impacts were caused by hydraulic fracturing activities or 

other sources. Water samples have been taken from domestic wells, springs, ponds, and streams 

near gas well pads. Figure 33 shows the sampling locations, which were primarily chosen based on 

individual homeowner complaints or concerns regarding potential adverse impacts to water 

resources from nearby hydraulic fracturing activities. 

145



Figure 33. Location of sampling sites in Bradford and Susquehanna Counties, Pennsylvania. Samples were taken in 

Susquehanna County during the first round of sampling. Later rounds of sampling are focused only in Bradford 

County. 

In addition to the analytes described in Section 7.1.1, the stable isotope compositions of carbon and 

hydrogen in dissolved methane and of carbon in dissolved inorganic carbon are being measured to 

determine the potential origin of the methane (i.e., biogenic versus thermogenic). 79 Since methane 

is known to be naturally present in the ground water of northeastern Pennsylvania, it is critical to 

understand the origin of any methane detected as part of this case study. Samples are also being 

analyzed for radium-226, radium-228, and gross alpha and beta radiation, as they may be potential 

indicators of hydraulic fracturing impacts to ground water in northeast Pennsylvania. Together, 

these measurements support the objective of determining if ground water resources have been 

impacted by hydraulic fracturing activities or other sources of contamination. 


Two rounds of sampling have been completed from 34 domestic wells, two springs, one pond, and 

one stream. The first sampling round was conducted in October and November of 2011 and the 

second round in April and May of 2012. The locations of sampling sites are displayed in Figure 33. 

79 Biogenic methane is formed as methane-producing microorganisms chemically break down organic material. 

Thermogenic methane results from the geologic formation of fossil fuel. 

146




A third round of sampling to verify data collected from the first two rounds of sampling is already 

planned. Additional sampling locations may be included and there may be future rounds of 

sampling as analytical data from the first three rounds are evaluated and additional pertinent 

information becomes available. More focused investigations may also be conducted, if warranted, at 

locations where potential impacts associated with hydraulic fracturing are suspected. 


The initial QAPP for this case study, “Hydraulic Fracturing Retrospective Case Study, Bradford- 

Susquehanna Couties, PA,” was approved by the designated EPA QA Manager on October 3, 2011 

(US EPA, 2012m). A revision to the QAPP was made prior to the second sampling event and was 

approved on April 12, 2012, to address the addition of analytes such as radium-226, radium-228, 

lithium, and thorium; updated project organization and accreditation information; and clarification 

on some sampling and laboratory QA/QC issues. There have been no significant deviations from the 

QAPP during any sampling event, and therefore no impact to data quality. A field TSA was 

conducted on October 27, 2011; no findings were identified. See Section 7.1.1 for information 

related to the laboratory TSAs. 





147



7.5. Washington County, Pennsylvania 


Washington County, located about 30 miles southwest of Pittsburgh, Pennsylvania, has a population 

of about 208,000 with approximately 240 people per square mile (USCB, 2010e). Figure 34 shows 

its position in the western region of the Marcellus Shale. Recently, oil and gas exploration and 

production in this area have increased, primarily due to production of natural gas from the 

Marcellus Shale using hydraulic fracturing. 

Figure 34. Extent of the Marcellus Shale, which underlies large portions of New York, Ohio, Pennsylvania, and West 

Virginia (US EIA, 2011d; USCB, 2012a, c). The case study focuses on reported changes in drinking water quality and 

quantity in Washington County, Pennsylvania. 

The location of this case study was chosen in response to homeowner complaints about changes to 

water quality and water quantity in Washington County. Residents in several areas of Washington 

County have reported impacts to their private drinking water wells, specifically increased turbidity, 

discoloration of sinks, and transient organic odors. Sampling locations were selected in May 2011 

by interviewing individuals about their water quality and the timing of any possible water quality 

148



changes in relation to gas production activities. Potential sources of ground water and surface 

water contamination under consideration at this case study site may include activities associated 

with oil and gas production (such as leaking or abandoned pits), gas well completion and 

enhancement techniques, and improperly plugged and abandoned wells, as well as activities 

associated with residential and agricultural practices. 


Geology. Washington County, like Bradford County, is located in the Appalachian Basin. The geology 

of this area of Pennsylvania consists of thick sequences of Paleozoic Era (Appendix D) sedimentary 

formations that dip and thicken to the southeast toward the basin axis. The surface geology in 

Washington County consists of Quaternary alluvial deposits, predominantly in stream valleys of the 

county. Alluvial deposits are generally less than 60 feet thick and consist of clay, silt, sand, and 

gravel derived from local bedrock. The formations of the Appalachian Basin are derived from a 

variety of clastic and biochemical sedimentary deposits, ranging from terrestrial swamps to nearshore 

environments and deep marine basins, which created shales, limestones, sandstones, 

coalbeds, and other sedimentary rocks (Shultz, 1999). As previously noted, the Marcellus Shale 

formation is of particular importance to recent gas exploration and production in the Appalachian 

Basin. In Washington County, the depth to the Marcellus Shale ranges from about 5,000 to 7,000 

feet below ground surface (Marcellus Center for Outreach and Research, 2012a). The thickness of 

the Marcellus Shale in Washington County is less than 150 feet (Marcellus Center for Outreach and 

Research, 2012b). 

Water Resources. The rivers and streams of Washington County drain into the Ohio River to the 

west. Drinking water aquifers in the county exist in both the alluvial deposits overlying bedrock in 

the stream valleys and in the bedrock. Ground water flow in the shallow aquifer system generally 

follows the topography, moving from recharge areas near hilltops to discharge areas in valleys. 

Background information on the geology and hydrology of Washington County is summarized from 

reports published by Newport (1973) and Williams et al. (1993). Ground water in Washington 

County occurs in both confined and unconfined aquifers, with well yields ranging from a fraction of 

a gallon per minute to over 350 gallons per minute. In this area, water-bearing zones are generally 

no deeper than 150 feet below ground surface, and the depth to water varies from 20 to 60 feet 

below land surface depending on topographic setting. In addition to alluvial aquifers, ground water 

is derived from bedrock aquifers, including the Monongahela Group, the Conemaugh Group, and the 

Greene and Washington formations, which consist of limestones, shales, and sandstone units. In 

general, ground water derived from these formations has yields ranging from less than 1 to over 70 

gallons per minute, and the formations range in depth from less than 40 feet to over 400 feet. The 

Conemaugh Group generally provides the greatest yield; the median yield for wells in this aquifer is 

5 gallons per minute. 

The quality of ground water in Washington County is variable and depends on factors such as 

formation lithology and residence time. For example, recharge ground water sampled from hilltops 

and hillsides is typically calcium-bicarbonate type and usually low in TDS (about 500 milligrams 

per liter). Ground water from valley settings in areas of discharge is typically sodium-bicarbonate 

or sodium-chloride type, with higher TDS values (up to 2,000 milligrams per liter). Williams et al. 

149



(1993) report that background concentrations of iron and manganese in the ground water from 

Washington County are frequently above the EPA’s secondary MCLs: over 33% of water samples 

had iron concentrations greater than 0.3 milligrams per liter, and 30% of water samples had 

manganese concentrations above 0.05 milligrams per liter. Hard water was also reported as being a 

common problem in the county, with TDS levels in more than one-third of the wells sampled by 

Williams et al. (1993) exceeding 500 milligrams per liter. Arsenic, cadmium, chromium, copper, 

lead, mercury, selenium, silver, and zinc were also detected at low levels. Historically, ground water 

quality in Washington County has been altered due to drainage from coal mining operations 

(Newport, 1973). Additionally, fresh water aquifers in some locations have been contaminated by 

brine from deeper non-potable aquifers through historic oil and gas wells that were improperly 

abandoned or have corroded casings (Newport, 1973). 

Oil and Gas Exploration and Production. The oil and gas development in Washington County dates 

back to the 1800s, but generally did not target the Marcellus Shale (Ashley and Robinson, 1922). 

The first test gas well into the Marcellus Shale was drilled in Mount Pleasant Township in 

Washington County in 2003 and was hydraulically fractured in 2004. Data provided by the 

Pennsylvania Department of Environmental Protection indicate that the number of permitted gas 

wells in the Washington County area of the Marcellus Shale increased rapidly, from 10 wells in 

2005 to 205 wells in 2009 (MarcellusGas.Org, 2012b). From 2009 to 2012, the number of newly 

permitted wells per year has remained below 240 (MarcellusGas.Org, 2012c). The anticipated 

water usage for all permitted wells in Washington County is estimated to be nearly 5 billion gallons 

(MarcellusGas.Org, 2012a). 


Methods for sampling ground water and surface water are described in detail in the QAPP (US EPA, 

2012n). Samples have been taken from domestic wells and surface water bodies. The EPA chose 

sampling locations by interviewing individuals about their water quality and the timing of water 

quality changes in relation to gas production activities. The locations of sampling sites are shown in 

Figure 35. 

150



Figure 35. Sampling locations in Washington County, Pennsylvania. 

Water samples collected at these locations are being analyzed for the chemicals listed in Section 

7.1.1 as well as the chemicals listed in the QAPP (US EPA, 2012n). Together these measurements 

support the objective of determining if ground water resources have been impacted by hydraulic 

fracturing activities, or other sources of contamination. 


Two rounds of sampling have been completed: the first in July 2011 and the second in March 2012. 

During July 2011, 13 domestic wells and three surface water locations (small streams and spring 

discharges) were sampled. During March 2012, 13 domestic wells and two surface water locations 

were sampled. The locations of sampling sites are displayed in Figure 35. 


Additional sampling rounds will be conducted to verify data collected from the first two rounds of 

sampling. Additional sampling locations may be included in the future as analytical data is 

evaluated and additional pertinent information becomes available. More focused investigations 

may also be conducted, if warranted, at locations where impacts associated with hydraulic 

fracturing may have occurred. 


The initial QAPP for this case study, “Hydraulic Fracturing Retrospective Case Study, Marcellus 

Shale, Washington County, PA,” was approved by the designated EPA QA Manager on July 21, 2011 

(US EPA, 2012n). A revision to the QAPP was made before the second sampling event and was 

151



approved on March 5, 2012, to update project organization, lab accreditation information, sampling 

methodology, to add radium isotope analyses and gross alpha/beta analyses, to modify critical 

analytes, and to change the analytical method for determining water isotope values. There have 

been no significant deviations from the QAPP during any sampling event, and therefore no impact 

on data quality. A field TSA was conducted on March 26, 2011; no findings were identified. See 

Section 7.1.1 for information related to the laboratory TSAs. 





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7.6. Wise County, Texas 


Wise County, Texas, is mostly rural, with a total population of about 60,000 and about 66 people 

per square mile (USCB, 2010f). Current gas development activities in Wise County are in the 

Barnett Shale, which is an unconventional shale in the Fort Worth Basin adjoining the Bend Arch 

Basin of north-central Texas. Figure 36 shows the extent of the Barnett Shale in Texas. In recent 

years, gas production in Wise County has increased due to improvements in horizontal drilling and 

hydraulic fracturing technologies. 

Figure 36. Extent of the Barnett Shale in north-central Texas (US EIA, 2011e; USCB, 2012a, c). The case study 

focuses on three distinct locations within Wise County. 

The intent of this case study is to investigate homeowner concerns about changes in the ground 

water quality in Wise County that may be related to the recent increase in the hydraulic fracturing 

of oil and gas wells. Sampling locations in Wise County were chosen based on reported complaints 

of changes in drinking water quality and are clustered in three distinct locations: two near Decatur 

and one near Alvord. Homeowners in the two locations near Decatur reported changes in water 

153



quality, including changes in turbidity, color, smell, and taste. Homeowners near Alvord also 

reported changes in drinking water quality, although no more specific concerns were identified. 

Concerns about potential hydraulic fracturing impacts to ground water resources in Wise County 

are related to flowback fluid discharge to shallow aquifers, gas migration to shallow aquifers, spills 

on well pads, and leaking impoundments. Residential or agricultural practices, or aquifer 

drawdown unrelated to oil and gas development, may also be sources of ground water 

contamination at these sites. 


Geology. Wise County is located in the Bend Arch-Fort Worth Basin, which was formed during the 

late Paleozoic Ouachita Orogeny by the convergence of Laurussia and Gondwana in a narrow, 

restricted, inland seaway (Bruner and Smosna, 2011). The stratigraphy of the Bend Arch-Fort 

Worth Basin is characterized by limestones, sandstones, and shales. The Barnett Shale is of 

Mississippian age (Appendix D) and extends throughout the Bend Arch-Fort Worth Basin: south 

from the Muenster Arch, near the Oklahoma border, to the Llano Uplift in Burnet County and west 

from the Ouachita Thrust Front, near Dallas, to Taylor County (Bruner and Smosna, 2011). The 

Barnett Shale ranges from about 50 to 1,000 feet thick and occurs at depths ranging from 4,000 to 

8,500 feet (Bruner and Smosna, 2011). In the northeastern portion of the Fort Worth Basin, the 

Barnett Shale is divided by the presence of the Forestburg Limestone, but this formation tapers out 

toward the southern edge of Wise County (Bruner and Smosna, 2011). The Barnett Shale is 

bounded by the Chappel Limestone below it and the Marble Falls Limestone above it (Bruner and 

Smosna, 2011). A recent estimate of the potential total gas yield was 820 billion cubic feet of gas per 

square mile, which is a significant increase from earlier estimates (Bruner and Smosna, 2011). 

Water Resources. Wise County is drained by the Trinity River. Residents in the county often rely on 

the Trinity Aquifer as a major source of drinking water. In addition to drinking water, the Trinity 

Aquifer is also used for irrigation, industrial water, and hydraulic fracturing source water. The 

aquifer is composed of three formations, deposited in the Cretaceous: Paluxy, Glen Rose, and Twin 

Mountain (Nordstrom, 1982; Reutter and Dunn, 2000; Scott and Armstrong, 1932). In the northern 

part of Wise County, the Glen Rose formation pinches out, leaving only the Paluxy and Twin 

Mountain Formations, which together are occasionally referred to as the Antlers Formation 

(Nordstrom, 1982; Reutter and Dunn, 2000). The composition of the Paluxy Formation is fine sand, 

sandy shale, and shale and yields small to moderate quantities of water (Nordstrom, 1982). The 

Glen Rose Formation is composed of limestone, marl, shale, and anhydrite. The Glen Rose yields 

small quantities of water in localized areas (Nordstrom, 1982). Finally, the composition of the Twin 

Mountain Formation is fine to coarse sand, shale, clay, and basal gravel and conglomerate. This 

formation yields moderate to large quantities of water (Nordstrom, 1982). The Trinity Aquifer is 

overlain by the Walnut Creek Formation and is underlain by Graham Formation, both of which act 

as confining layers (Scott and Armstrong, 1932). Before modern water usage, it was artesian. 

Table 54 summarizes background water quality data for the Trinity Aquifer in Wise County 

(Reutter and Dunn, 2000). The water quality is expected to be slightly different in the northern 

portion of the county than the southern portion of the county due to the “pinching out” of the Glen 

Rose Formation. From the reported data, the major water types in Wise County are calcium 

154



bicarbonate, calcium chloride, and sodium bicarbonate (Reutter and Dunn, 2000). All three water 

types are present in northern Wise County, but only the calcium bicarbonate and calcium chloride 

water types were observed in southern Wise County. The data collected at study locations will be 

compared to this compiled background data as part of the initial screening to determine if any 

contamination has occurred in study locations. 

Table 54. Background water quality data for all of Wise County, Texas, and its northern and southern regions 

(Reutter and Dunn, 2000). Range of concentrations shown, with median values reported in parentheses. 

Parameter 

Units 

Wise County 

Concentration Ranges 

North Wise 

County 

South Wise 

County 

Alkalinity mg CaCO 3 /L 130–430 (335) 190–430 (330) 130–420 (360) 

Aluminum µg/L 1–5 (2) 2–5 (2) 1–5 (2) 

Ammonia mg N/L




Parameter 

Specific 

conductance 

Units 

Wise County 

Concentration Ranges 

North Wise 

County 

South Wise 

County 

µS/cm 710–4,590 (913) 71–4,590 (911) 510–2,380 (914) 

Sulfate mg/L 10–250 (46) 26–250 (45) 10–160 (46) 

Uranium µg/L



Figure 37. Location of sampling sites in Wise County, Texas. 

Water samples collected at these locations are being analyzed for the chemicals listed in Section 

7.1.1 as well as the chemicals listed in the QAPP (US EPA, 2012p). Together these measurements 

support the objective of determining if ground water resources have been impacted by hydraulic 

fracturing activities, or other sources of contamination. 


Two rounds of sampling have been conducted at all locations in Wise County: one round in 

September 2011 and one round in March 2012. The September 2011 sampling event included 11 

domestic wells, one industrial well, and three surface water (pond) samples. The March 2012 

sampling event included the same wells as the September 2011 sampling event, with an additional 

four domestic wells and the loss of one domestic well. The locations of all sampling sites are 

displayed in Figure 37. 


Additional sampling rounds will be conducted to verify data collected from the first two rounds of 

sampling. Additional sampling locations may be included in the future as analytical data are 

evaluated and additional pertinent information becomes available. More focused investigations 

may also be conducted, if warranted, at locations where impacts may have occurred. 

157




The initial QAPP for this case study, “Hydraulic Fracturing Retrospective Case Study, Wise, TX,” was 

approved by the designated EPA QA Manager on June 20, 2011 (US EPA, 2012p). A revision to the 

QAPP was made before the second sampling event and was approved on February 27, 2012. The 

revision included the addition of isotopic analysis, USGS laboratory information, 82 revised sampling 

locations, Region 8 laboratory accreditation status, geophysical measurement methods and QC, data 

qualifiers, personnel changes, and analytical method updates. A second revision was approved on 

May 25, 2012, for the next sampling event to include the Phase 2 sampling information, the method 

for qualifying field blanks, and the modified sampling schedule. The second QAPP revision also 

replaced EPA Method 200.7 with 6010C and replaced metals QC criteria with revised criteria. A 

third revision to the QAPP was approved on September 10, 2012, to add information on March 

2012 sampling, add strontium and stable water isotopes to analytes list, and delete diesel range 

organics and gasoline range organics. The third QAPP revision also replaced EPA Method 6010C 

with 200.7. 83 There have been no significant deviations from the QAPP during any sampling event, 

and therefore no impact on data quality. A field TSA was conducted on September 21, 2011; no 

findings were identified. See Section 7.1.1 for information related to the laboratory TSAs. 





82 USGS provided isotope support for the Wise County retrospective case study. A detailed account of the role of USGS can 

be found in Appendix A of the Wise County QAPP. 

83 

EPA Method 200.7 was referenced in the initial QAPP and the first QAPP revision. It was changed in the second QAPP 

revision to EPA Method 6010C, but since then it was determined by QA staff that the use of 200.7 as the “base” method 

was appropriate as 200.7 incorporates 6010C by reference. 

158



8. Conducting High-Quality Science 

The EPA ensures that its research activities result in high-quality science through the use of QA and 

peer review activities. Specific QA activities performed by the EPA ensure that the agency’s 

environmental data are of sufficient quantity and quality to support the data’s intended use. Peer 

review ensures that the data are sound and used appropriately. The use of QA measures and peer 

review helps ensure that the EPA conducts high-quality science that can be used to inform 

policymakers, industry, and the public. 

8.1. Quality Assurance 

All agency research projects that generate or use environmental data to make conclusions or 

recommendations must comply with the EPA QA program requirements. The EPA laboratories and 

external organizations involved with the generation or use of environmental data are supported by 

QA professionals who oversee the implementation of the QA program for their organization. To 

ensure scientifically defensible results, this study complies with the agency-wide Quality Policy CIO 

2106 (US EPA, 2008), EPA Order CIO 2105.0 (US EPA, 2000a, c), the EPA’s Information Quality 

Guidelines (US EPA, 2002), the EPA’s Laboratory Competency Policy (US EPA, 2004a), and Chapter 

13 of the Office of Research and Development’s Policies and Procedures Manual (US EPA, 2006). 

Given the cross-organizational nature of this study, a Quality Management Plan was developed (US 

EPA, 2012t) and a Program QA Manager was chosen to coordinate a rigorous QA approach and 

oversee its implementation across all participating organizations within the EPA. The Quality 

Management Plan defines the QA-related policies, procedures, roles, responsibilities, and 

authorities for the study and documents how the EPA will plan, implement, and assess the 

effectiveness of its QA and QC operations. In light of the importance and organizational complexity 

of the study, the Quality Management Plan was created to make certain that all research be 

conducted with integrity and strict quality controls. 

The Quality Management Plan sets forth the following rigorous QA approach: 

• Individual research projects must comply with agency requirements and guidance for 

QAPPs. 

• TSAs and audits of data quality will be conducted for individual research projects as 

described in the QAPPs. 

• Performance evaluations of analytical systems will be conducted. 

• Products will undergo QA review. Applicable products may include reports, journal 

articles, symposium/conference papers, extended abstracts, computer products/ 

software/models/databases, and scientific data. 

• Reports will have readily identifiable QA sections. 

Research records will be managed according to EPA Records Schedule 501, “Applied and Directed 

Scientific Research”(US EPA, 2011c). 

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The Quality Management Plan applies to all research activities conducted under the EPA’s Study of 

the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources. More information about 

specific QA protocols, including management, organization, quality-system components, personnel 

qualification and training, procurement of items and services, documentation and records, 

computer requirements, planning, implementation, assessment, and quality improvement, can be 

found in the Quality Management Plan. 84 

Project-specific details of individual research projects are documented in a QAPP. All work 

performed or funded by the EPA that involves the acquisition of environmental data must have an 

approved QAPP. The QAPP documents the planning, implementation, and assessment procedures 

for a particular project, as well as any specific QA and QC activities. It integrates all the technical 

and quality aspects of the project in order to provide a guide for obtaining the type and quality of 

environmental data and information needed for a specific decision or use. Quality assurance project 

plans are living documents that undergo revisions as needed. Individual QAPPs for the various 

research projects included in this study are available on the study website 

(http://www.epa.gov/hfstudy) and are summarized in Appendix C. 

Regular technical assessments of project operation, systems, and data related to the study are 

conducted as detailed in the Quality Management Plan. A technical assessment is “a systematic and 

objective examination of a project to determine whether environmental data collection activities 

and related results comply with the project’s QAPP, whether the activities are implemented 

effectively, and whether they are sufficient and adequate to achieve QAPP’s data quality goals” (US 

EPA, 2000b). Assessment components include quality system assessments, technical system 

assessments, verification of data, audits of data quality, and surveillance. More details about 

assessments and audits required for this study can be found in the Quality Management Plan and 

project-specific QAPPs. 

Quality Assurance and Projects Involving the Generation of New Data. Research projects that 

generate new data (e.g., case studies, laboratory studies, some toxicity assessments) will contribute 

to the growing body of scientific literature about environmental issues associated with hydraulic 

fracturing. The QA/QC procedures detailed in these QAPPs meet the requirements of the hydraulic 

fracturing Quality Management Plan, detailed above, and also focus on those practices necessary for 

assuring the quality of measurement data generated by the EPA. Samples must be collected, 

preserved, transported, and stored in a manner that retains their integrity; these issues are 

addressed in individual QAPPs. Also described in QAPPs are the methods used for sample analysis, 

including details about the appropriate frequency of calibration of analytical instrumentation and 

measurement devices. Quality control samples are identified that can be used to check for potential 

contamination of samples and to check for measurement errors that can be caused by difficult 

sample matrices. The QAPPs for generation of new data provide details on the logistics of who, 

where, when and how new data will be generated. 

84 Research initiated prior to the implementation of the study-specific Quality Management Plan was conducted under 

Quality Management Plans associated with each of the EPA Office of Research and Development’s individual labs and 

centers. 

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Quality Assurance and Projects Involving Existing Data. Research projects that involve acquiring and 

analyzing existing data (i.e., data that are not new data generated by or for the EPA) must conform 

to the requirements of the Quality Management Plan, including the development of a QAPP. The 

focus of QAPPs for existing data is on setting criteria that will filter out any data that are of 

insufficient quality to meet project needs. This starts with describing the process for locating and 

acquiring the data. How the data will be evaluated for their planned use and how the integrity of the 

data will be maintained throughout the collection, storing, evaluation, and analysis processes are 

also important features of a QAPP for existing data. 

Quality Assurance and Report Preparation. Quality assurance requirements also extend to the two 

primary products of this study: this progress report and the report of results. As required by the 

Quality Management Plan, this progress report has undergone QA review before its release, and the 

report of results will do the same. These requirements serve to ensure that the reports are 

defensible and scientifically sound. 

8.2. Peer Review 

Peer review, an important part of every scientific study, is a documented critical review of a specific 

scientific and/or technical work product (e.g., paper, report, presentation). It is an in-depth 

assessment of the assumptions, calculations, extrapolations, alternate interpretations, 

methodology, acceptance criteria, and conclusions in the work product and the documents that 

support them. Peer review is conducted by individuals (or organizations) independent of those who 

performed the work and equivalent in technical expertise (US EPA, 2012e; US OMB, 2004). 

Feedback from the review process is used to revise the draft product to make certain the final work 

product reflects sound technical information and analyses. 

Peer review can take many forms depending on the nature of the work product. Work products 

generated through the EPA’s Study of the Potential Impacts of Hydraulic Fracturing on Drinking 

Water Resources will be subjected to both internal and external peer review. Internal peer review 

occurs when work products are reviewed by independent experts within the EPA, while external 

peer review engages experts outside of the agency, often through scientific journals, letter reviews, 

or ad hoc panels. 

The EPA often engages the Science Advisory Board, an external federal advisory committee, to 

conduct peer reviews of high-profile scientific matters relevant to the agency. Members of an ad hoc 

panel convened under the auspices of the Science Advisory will provide comment on this progress 

report. 85 Panel members are nominated by the public and chosen based on factors such as technical 

expertise, knowledge, experience, and absence of any real or perceived conflicts of interest to 

create a balanced review panel. In August 2012, the EPA issued a Federal Register notice requesting 

public nominations for technical experts to form a Science Advisory Board ad hoc panel to provide 

advice on the status of the research described in this progress report (US EPA, 2012v). This panel is 

85 Information about this process is available at http://yosemite.epa.gov/sab/sabproduct.nsf/ 

02ad90b136fc21ef85256eba00436459/b436304ba804e3f885257a5b00521b3b!OpenDocument. 

161



also expected to review the report of results, which has been classified as a Highly Influential 

Scientific Assessment. 86 

86 The Office of Management and Budget’s Peer Review Bulletin (US OMB, 2004) defines Highly Influential Scientific 

Assessments as scientific assessments that could (1) have a potential impact of more than $500 million in any year or (2) 

are novel, controversial, or precedent-setting or have significant interagency interest. The Peer Review Bulletin describes 

specific peer review requirements for Highly Influential Scientific Assessments. 

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9. Research Progress Summary and 

Next Steps 

This report describes the progress made for each of the research projects conducted as part of the 

EPA’s Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources. This 

chapter provides an overview of the progress made for each research activity as well as the 

progress made for each stage of the water cycle presented in Section 2.1. It also describes, in more 

detail, the report of results. 

9.1. Summary of Progress by Research Activity 

The EPA is using a transdisciplinary research approach to investigate the potential relationship 

between hydraulic fracturing and drinking water resources. This approach includes compiling and 

analyzing data from existing sources, evaluating scenarios using computer models, carrying out 

laboratory studies, assessing the toxicity associated with hydraulic fracturing-related chemicals, 

and conducting case studies. 

Analysis of Existing Data. To date, data from seven sources have been obtained for review and 

ongoing analysis, including: 

• Information provided by nine hydraulic fracturing service companies. 

• 333 well files supplied by nine oil and gas operators. 

• Over 12,000 chemical disclosure records from FracFocus, the national hydraulic fracturing 

chemical registry managed by the Ground Water Protection Council and the Interstate Oil 

and Gas Compact Commission. 

• Spill reports from four different sources, including databases from the National Response 

Center, Colorado, New Mexico, and Pennsylvania. 

As part of its literature review, the EPA has compiled, and continues to search for, literature 

relevant to the secondary research questions listed in Section 2.1. This includes documents 

provided by stakeholders and recommended by the Science Advisory Board during its review of the 

draft study plan. 87 A Federal Register notice requesting peer-reviewed data and publications 

relevant to the study, including information on advances in industry practices and technologies, has 

recently been published (US EPA, 2012u). 

Scenario Evaluations. Potential impacts to drinking water sources from withdrawing large volumes 

of water in both a semi-arid and a humid river basin—the Upper Colorado River Basin in the west 

and the Susquehanna River Basin in the east—are being assessed. Additionally, complex computer 

models are being used to explore the possibility of subsurface gas and fluid migration from deep 

shale formations to overlying aquifers in six different scenarios. These scenarios include poor well 

87 Additional information on the Science Advisory Board review of the EPA’s Draft Plan to Study the Potential Impacts of 

Hydraulic Fracturing on Drinking Water Resources is available at http://www.epa.gov/hfstudy/peer-review.html. 

163



construction and hydraulic communication via fractures (natural and created) and nearby existing 

wells. As a first step, the subsurface migration simulations will examine realistic scenarios to assess 

the conditions necessary for hydraulic communication rather than the probability of migration 

occurring. In a separate research project, the EPA is using surface water transport models to 

estimate concentrations of bromide and radium at public water supply intakes downstream from 

wastewater treatment facilities that discharge treated hydraulic fracturing wastewater. 

Laboratory Studies. The ability to analyze and determine the presence and concentration of 

chemicals in environmental samples is critical to the EPA’s study. In most cases, standard EPA 

methods are being used for laboratory analyses. In other cases, however, standard methods do not 

exist for the low-level detection of chemicals of interest or for use in the complex matrices 

associated with hydraulic fracturing wastewater. Where necessary, existing analytical methods are 

being tested, modified, and verified for use in this study and by others. Analytical methods are 

currently being tested and modified for several classes of chemicals, including glycols, acrylamides, 

ethoxylated alcohols, DBPs, radionuclides, and inorganic chemicals. 

Laboratory studies focusing on the potential impacts of inadequate treatment of hydraulic 

fracturing wastewater on drinking water resources are being planned and conducted. The studies 

include assessing the ability of hydraulic fracturing wastewater to create brominated DBPs and 

testing the efficacy of common wastewater treatment processes on removing selected 

contaminants from hydraulic fracturing wastewater. Samples of surface water, raw hydraulic 

fracturing wastewater, and treated effluent have been collected for the source apportionment 

studies, which aim to identify the source of high chloride and bromide levels in rivers accepting 

treated hydraulic fracturing wastewater. 

Toxicity Assessment. The EPA has evaluated data to identify chemicals reportedly used in hydraulic 

fracturing fluids from 2005 to 2011 and chemicals found in flowback and produced water. 

Appendix A contains tables of these chemicals, with over 1,000 chemicals identified. Chemical, 

physical, and toxicological properties have been compiled for chemicals with known chemical 

structures. Existing models are being used to estimate properties in cases where information is 

lacking. At this time, the EPA has not made any judgment about the extent of exposure to these 

chemicals when used in hydraulic fracturing fluids or found in hydraulic fracturing wastewater, or 

their potential impacts on drinking water resources. 

Case Studies. Two rounds of sampling at all five retrospective case study locations have been 

completed. In total, water samples have been collected from over 70 domestic water wells, 15 

monitoring wells, and 13 surface water sources, among others. A third round of sampling is 

expected to occur this fall in Las Animas and Huerfano Counties, Colorado; Dunn County, North 

Dakota; and Wise County, Texas. Additional sampling in Bradford and Washington Counties, 

Pennsylvania, is projected to take place in spring 2013. 

The EPA continues to work with industry partners to plan and begin research activities for 

prospective case studies. 

164



9.2. Summary of Progress by Water Cycle Stage 

Figures 38 and 39 illustrate the research underway for each stage of the hydraulic fracturing water 

cycle. The fundamental research questions and research focus areas are briefly described below for 

each water cycle stage; for more detail on the stages of the hydraulic fracturing water cycle and 

their associated research projects, see Section 2.1. 

Water Acquisition: What are the possible impacts of large volume water withdrawals from ground 

and surface waters on drinking water resources Work in this area focuses on understanding the 

volumes and sources of water needed for hydraulic fracturing operations, and the potential impacts 

of water withdrawals on drinking water quantity and quality. Effects of recently emerging trends in 

water recycling will be considered in the report of results. 

Chemical Mixing: What are the possible impacts of surface spills on or near well pads of hydraulic 

fracturing fluids on drinking water resources Spill reports from several databases are being 

reviewed to identify volumes and causes of spills of hydraulic fracturing fluids and wastewater. 

Information on the chemicals used in hydraulic fracturing fluids and their known chemical, 

physical, and toxicological properties has been compiled. 

Well Injection: What are the possible impacts of the injection and fracturing process on drinking water 

resources Work currently underway is focused on identifying conditions that may be associated 

with the subsurface migration of gases and fluids to drinking water resources. The EPA is exploring 

gas and fluid migration due to inadequate well construction as well as the presence of nearby 

natural faults and fractures or man-made wells. 

Flowback and Produced Water: What are the possible impacts of surface spills on or near well pads of 

flowback and produced water on drinking water resources As with chemical mixing, research in this 

area focuses on reviewing spill reports of flowback and produced water as well as collecting 

information on the composition of hydraulic fracturing wastewater. Known chemical, physical, and 

toxicological properties of the components of flowback and produced water are being compiled. 

Wastewater Treatment and Waste Disposal: What are the possible impacts of inadequate treatment of 

hydraulic fracturing wastewater on drinking water resources Work in this area focuses on 

evaluating treatment and disposal practices for hydraulic fracturing wastewater. Since some 

wastewater is known to be discharged to surface water after treatment in POTWs or commercial 

treatment systems, the EPA is investigating the efficacy of common treatment processes at 

removing selected components in flowback and produced water. Potential impacts to downstream 

public water supplies from discharge of treated hydraulic fracturing wastewater are also being 

investigated, including the potential for the formation of Br-DBPs. 

165



Water Acquisition Chemical Mixing Well Injection 


Review and summarize literature on: 

• Volumes and sources of water used in 

hydraulic fracturing fluids 

• Local impacts to water availability in 

areas with hydraulic fracturing activity 

• Water quality impacts from ground 

and surface water withdrawals 


Summarize data provided by nine 

hydraulic fracturing service companies 

on volumes and sources of water used 

in hydraulic fracturing fluids 


Summarize data from 333 well files on 

volumes and source of water used in 



Compile and summarize total water 

volumes reported in FracFocus by 

geographic location, well depth, water 

types, and oil/gas production 



• Spills of hydraulic fracturing fluids or 

chemical additives 

• Chemicals used in hydraulic fracturing 

fluids 

• Environmental fate and transport of 

selected chemicals in hydraulic 

fracturing fluids 


Compile and evaluate spill information 

from three state databases (CO, NM, 

PA) and one national database (NRC) 


Evaluate information on: 

• Spills of hydraulic fracturing fluids or 

chemical additives 

• Chemicals used in hydraulic fracturing 

fluids from 2005 to 2010 


Evaluate spill data from 333 well files 


Compile a list of chemicals reported in 

FracFocus and summarize chemical 

usage by frequency and geographic 

location 


Review and summarize literature on 

possible subsurface migration due to: 

• Faulty well construction 

• Nearby natural or man-made conduits 


Review and summarize standard 

operating procedures for information on: 

• Practices related to establishing the 

mechanical integrity of wells being 

hydraulically fractured 

• Procedures used during injection of 

the fracturing fluid 


Review well construction data found in 

well files to assess the effectiveness of 

current well construction practices at 

isolating the wellbore from surrounding 

ground water 





Case Studies 

Figure 38a. Summary of research projects underway for the first three stages of the hydraulic fracturing water cycle. 

166



Water Acquisition Chemical Mixing Well Injection 


• Summarize data on water usage for 

hydraulic fracturing in a semi-arid 

climate (Upper Colorado River Basin) 

and a humid climate (Susquehanna 

River Basin) 

• Use watershed models to explore 

water availability for public water 

supplies under a variety of scenarios, 

focusing on water usage in the Upper 

Colorado and Susquehanna River 

Basins 





Case Studies 

Analytical Method Development 

Develop analytical methods for the 

detection of selected chemicals reported 

to be in hydraulic fracturing fluids 


Compile or estimate chemical, physical, 

and toxicological properties for 

chemicals with known chemical 

structures that are reported to be in 


Retrospective Case Studies 

Consider spills of hydraulic fracturing 

fluids as a possible source of reported 

changes in water quality of local 

drinking water wells 

Subsurface Migration Modeling 

Apply computer models to explore the 

potential for gas or fluid migration from: 

• Incomplete well cementing or cement 

failure during hydraulic fracturing 

• Nearby wells and existing faults 


Consider potential impacts to drinking 

water sources from: 

• Relatively shallow hydraulic fracturing 

operations 

• Release of hydraulic fracturing fluids 

during the injection process 

• Poor well construction practices 

Figure 38b. Summary of research projects underway for the first three stages of the hydraulic fracturing water cycle. 

167



Flowback and Produced Water 



• Spills of flowback and produced water 

• Chemicals found in hydraulic 


• Environmental fate and transport of 

selected chemicals in hydraulic 



Compile spill information from three 

state databases (CO, NM, PA) and one 

national database (NRC) 


Evaluate information on: 

• Spills of flowback and produced water 

• Chemicals detected in hydraulic 



Evaluate spill data from 333 well files 





• Disposal practices associated with 

hydraulic fracturing wastewater 

• The treatability of hydraulic fracturing 

wastewater 

• Potential impacts to drinking water 

treatment facilities from surface 

discharge of treated hydraulic 



Summarize data from 333 well files on 

the volume and final disposition of 

flowback and produced water 


Summarize data on water types 

reported in FracFocus by volume and 

geographic location, focusing on 

recycled water 





Case Studies 

Figure 39a. Summary of research projects underway for the last two stages of the hydraulic fracturing water cycle. 

168



Flowback and Produced Water 

Analytical Method Development 

Develop analytical methods for the 

detection of selected chemicals in 

hydraulic fracturing wastewater matrices 


Compile or estimate chemical, physical, 

and toxicological properties for 

chemicals reported to be in hydraulic 



Consider spills or leaks of hydraulic 

fracturing wastewater as a possible 

source of reported changes in water 

quality of local drinking water wells 




Apply computer models to calculate 

downstream concentrations of selected 

contaminants at public water intakes 

under a variety of scenarios 

Source Apportionment Studies 

Collect samples from two wastewater 

treatment facilities and river networks 

and use computer models to identify the 

contribution of hydraulic fracturing 

wastewater to chemical concentrations 

found at downstream public water 

intakes 

Wastewater Treatability Studies 

Conduct laboratory experiments to 

identify the fate of selected chemicals 

found in flowback in common treatment 

processes, including conventional, 

commercial and water reuse processes 





Case Studies 


Conduct laboratory studies on the 

potential for treated hydraulic fracturing 

wastewater to form Br-DBPs during 

common drinking water treatment 

processes 

Figure 39b. Summary of research projects underway for the last two stages of the hydraulic fracturing water cycle. 

169



9.3. Report of Results 

This is a status report, describing the current progress made on the research projects that make up 

the agency’s Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources. 

Results from individual research projects will undergo peer review prior to publication either as 

articles in scientific journals or EPA reports. The EPA plans to synthesize results from the published 

reports with a critical literature review in a report of results that will answer as completely as 

possible the research questions identified in the Study Plan. The report of results has been 

determined to be a Highly Influential Scientific Assessment and will undergo peer review by the 

Science Advisory Board. Ultimately, the results of this study are expected to inform the public and 

provide policymakers at all levels with high-quality scientific knowledge that can be used in 

decision-making processes. 

The report of results will also be informed by information provided through the ongoing 

stakeholder engagement process described in Section 1.1. This process is anticipated to provide 

agency scientists with updates on changes in industry practices and technologies relevant to the 

study. While the EPA expects hydraulic fracturing technology to develop between now and the 

publication of the report of results, the agency believes that the research described here will 

provide timely information that will contribute to the state of knowledge on the relationship 

between hydraulic fracturing and drinking water resources. For example, some companies may 

adopt new injection or wastewater treatment technologies and practices, while others may 

continue to use current technologies and practices. Many of the practices, including wastewater 

treatment and disposal technologies used by POTWs, are not expected to change significantly 

between now and the report of results. 

Results from the study are expected to identify potential impacts to drinking water resources, if 

any, from water withdrawals, the fate and transport of chemicals associated with hydraulic 

fracturing, and wastewater treatment and waste disposal. Information on the toxicity of hydraulic 

fracturing-related chemicals is also being gathered. Although these data may be used to assess the 

potential risks to drinking water resources from hydraulic fracturing activities, the report of results 

is not intended to quantify risks. Results presented in the report of results will be appropriately 

discussed and all uncertainties will be described. 

The EPA will strive to make the report of results as clear and definitive as possible in answering all 

of the primary and secondary research questions, at that time. Science and technology evolve, 

however: the agency does not believe that the report of results will provide definitive answers on 

all research questions for all time and fully expects that additional research needs will be identified. 

9.4. Conclusions 

This report presents the EPA’s progress in conducting its Study of the Potential Impacts of Hydraulic 

Fracturing on Drinking Water Resources. Chapters 3 through 7 provide individual progress reports 

for each of the research projects that make up this study. Each project progress report describes the 

project’s relationship to the study, research methods, and status and summarizes QA activities. 

Information presented as part of this report cannot be used to draw conclusions about potential 

impacts to drinking water resources from hydraulic fracturing. 

170



The EPA is committed to conducting a study that uses the best available science, independent 

sources of information, and a transparent, peer-reviewed process that ensures the validity and 

accuracy of the results. The EPA will seek input from individual members of an ad hoc expert panel 

convened under the auspices of the EPA’s Science Advisory Board. Information about this process is 

available at http://yosemite.epa.gov/sab/sabproduct.nsf/02ad90b136fc21ef85256eba00436459/ 

b436304ba804e3f885257a5b00521b3b!OpenDocument. The individual members of the ad hoc 

panel will consider public comment. The EPA will consider feedback from the individual experts, as 

informed by the public’s comments, in the development of the report of results. 

171



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Watts, K. R. 2006a. Hydrostratigraphic Framework of the Raton, Vermejo, and Trinidad Aquifers in 

the Raton Basin, Las Animas County, Colorado. Scientific Investigations Report 2006-5129. 

US Geological Survey 37 p. Available at http://pubs.usgs.gov/sir/2006/5129/pdf/SIR06 

5129_508.pdf. Accessed December 3, 2012. 

194



Watts, K. R. 2006b. A Preliminary Evaluation of Vertical Separation between Production Intervals of 

Coalbed-Methane Wells and Water-Supply Wells in the Raton Basin, Huerfano and Las 

Animas Counties, Colorado, 1999-2004. Scientific Investigations Report 2006-5109. US 

Geological Survey. 15 p. Available at http://pubs.usgs.gov/sir/2006/5109/pdf/ 

sir2006_5109.pdf. Accessed December 3, 2012. 

Westat. 2011. Quality Assurance Project Plan v. 1.1 for Hydraulic Fracturing. Westat for US 

Environmental Protection Agency. Available at http://www.epa.gov/hfstudy/qapps.html. 


Williams, D. R., Felbinger, J. K. and Squillace, P. J. 1993. Water Resources and the Hydrologic Effects 

of Coal Mining in Washington County, Pennsylvania. Open-File Report 89-620. US Geological 

Survey, Lemoyne, Pennsylvania. 

Williams, J. E., Taylor, L. E. and Low, D. J. 1998. Hydrogeology and Groundwater Quality of the 

Glaciated Valleys of Bradford, Tioga, and Potter Counties, Pennsylvania. Water Resources 

Report 68. US Geological Survey and Pennsylvania Geological Survey. 98 p. Available at 

http://eidmarcellus.org/wp-content/uploads/2011/06/USGS-Bradford-Report.pdf. 


Ziemkiewicz, P. 2011. Wastewater from Gas Development: Chemical Signatures in the Monongahela 

River Basin. Proceedings of the US Environmental Protection Agency Technical Workshops 

for the Hydraulic Fracturing Study: Water Resources Management, Arlington, Virginia. 

Available at http://epa.gov/hfstudy/waterworkshop.html. Accessed November 30, 2012. 

195



Appendix A: Chemicals Identified in 

Hydraulic Fracturing Fluids and 

Wastewater 

This appendix contains tables of chemicals reported to be used in hydraulic fracturing fluids and 

chemicals detected in flowback and produced water. Sources of information include federal and 

state government documents, industry-provided data, and other reliable sources based on the 

availability of clear scientific methodology and verifiable original sources; the full list of 

information sources is available in Section A.1. The EPA at this time has not made any judgment 

about the extent of exposure to these chemicals when used in hydraulic fracturing fluids or found in 

hydraulic fracturing wastewater, or their potential impacts on drinking water resources. 

The tables in this appendix include information provided by nine hydraulic fracturing service 

companies (see Section 3.3), nine oil and gas operators (Section 3.4), and FracFocus (Section 3.5). 

Over 150 entries in Tables A-1 and A-2 were provided by the service companies, and roughly 60 

entries were provided by FracFocus; these entries were not included in easily obtained public 

sources. The nine oil and gas operators provided data on chemicals and properties of flowback and 

produced water; the chemicals and properties are listed in Tables A-3 and A-4. 

Much of the information provided in response to the EPA’s September 2010 information request to 

the nine hydraulic fracturing service companies was claimed as confidential business information 

(CBI) under the Toxic Substances Control Act. In many cases, the service companies have agreed to 

publicly release chemical names and Chemical Abstract Services Registration Numbers (CASRNs) in 

Table A-1. However, 82 chemicals with known chemical names and CASRNs continue to be claimed 

as CBI, and are not included in this appendix. In some instances, generic chemical names have been 

provided for these chemicals in Table A-2. 

In order to standardize chemical names, chemical name and structure annotation quality control 

methods have been applied to chemicals with CASRNs. 88 These methods ensure correct chemical 

names and CASRNs and include combining duplicates where appropriate. 

The EPA is creating a Distributed Structure-Searchable Toxicity (DSSTox) 89 chemical inventory for 

chemicals reported to be used in hydraulic fracturing fluids and/or detected in flowback and 

produced water. The hydraulic fracturing DSSTox chemical inventory will contain CASRNs, 

chemical names and synonyms, and structure data files (where available). The structure data files 

can be used with existing computer software to calculate physicochemical properties, as described 

in Chapter 6. 

88 Additional information on this process can be found at http://www.epa.gov/ncct/dsstox/ 

ChemicalInfQAProcedures.html. 

89 The DSSTox website provides a public forum for publishing downloadable, structure-searchable, standardized chemical 

structure files associated with chemical inventories or toxicity datasets of environmental relevance. For more 

information, see http://www.epa.gov/ncct/dsstox/. 

196



Table A-1 lists chemicals reported to be used in hydraulic fracturing fluids between 2005 and 2011. 

This table lists chemicals with their associated CASRNs. Structure data files are expected to be in 

the hydraulic fracturing DSSTox chemical inventory for some chemicals on Table A-1; these 

chemicals are marked with a “” in the “IUPAC Name and Structure” column. 

Table A-1. List of CASRNs and names of chemicals reportedly used in hydraulic fracturing fluids. Chemical 

structures and IUPAC names have been identified for the chemicals with an “” in the “IUPAC Name and Structure” 

column. A few chemicals have structures, but no assigned CASRNs; these chemicals have “NA” entered in the 

CASRN column. 

IUPAC 

CASRN Chemical Name Name and Reference 

Structure 

120086-58-0 

(13Z)-N,N-bis(2-hydroxyethyl)-N-methyldocos-13-en-1 

aminium chloride 

1 

123-73-9 (E)-Crotonaldehyde 1, 4 

2235-43-0 

[Nitrilotris(methylene)]tris-phosphonic acid pentasodium 

salt 

1 

65322-65-8 1-(1-Naphthylmethyl)quinolinium chloride 1 

68155-37-3 

1-(Alkyl* amino)-3-aminopropane *(42%C12, 26%C18, 

15%C14, 8%C16, 5%C10, 4%C8) 

68909-18-2 1-(Phenylmethyl)pyridinium Et Me derivs., chlorides 

8 

526-73-8 1,2,3-Trimethylbenzene 1, 4 

1, 2, 3, 4, 

6, 8 

95-63-6 1,2,4-Trimethylbenzene 1, 2, 3, 4, 5 

2634-33-5 1,2-Benzisothiazolin-3-one 1, 3, 4 

35691-65-7 1,2-Dibromo-2,4-dicyanobutane 1, 4 

95-47-6 1,2-Dimethylbenzene 4 

138879-94-4 

1,2-Ethanediaminium, N, N'-bis[2-[bis(2 

hydroxyethyl)methylammonio]ethyl]-N,N'bis(2 

hydroxyethyl)-N,N'-dimethyl-,tetrachloride 

1, 4 

57-55-6 1,2-Propanediol 1, 2, 3, 4, 8 

75-56-9 1,2-Propylene oxide 1, 4 

4719-04-4 1,3,5-Triazine-1,3,5(2H,4H,6H)-triethanol 1, 4 

108-67-8 1,3,5-Trimethylbenzene 1, 4 

123-91-1 1,4-Dioxane 2, 3, 4 

9051-89-2 

1,4-Dioxane-2,5-dione, 3,6-dimethyl-, (3R,6R)-, polymer 

with (3S,6S)-3,6-dimethyl-1,4-dioxane-2,5-dione and 

(3R,6S)-rel-3,6-dimethyl-1,4-dioxane-2,5-dione 

1, 4, 8 

124-09-4 1,6-Hexanediamine 1, 2 

6055-52-3 1,6-Hexanediamine dihydrochloride 1 

20324-33-8 

1-[2-(2-Methoxy-1-methylethoxy)-1-methylethoxy]-2 

propanol 

4 

78-96-6 1-Amino-2-propanol 8 


197




IUPAC 


Structure 

15619-48-4 1-Benzylquinolinium chloride 1, 3, 4 

71-36-3 1-Butanol 1, 2, 3, 4, 7 

112-30-1 1-Decanol 1, 4 

2687-96-9 1-Dodecyl-2-pyrrolidinone 1, 4 

3452-07-1 1-Eicosene 3 

629-73-2 1-Hexadecene 3 

111-27-3 1-Hexanol 1, 4, 8 

68909-68-7 

68442-97-7 

1-Hexanol, 2-ethyl-, manuf. of, by products from, distn. 

residues 

1H-Imidazole-1-ethanamine, 4,5-dihydro-, 2-nortall-oil 

alkyl derivs. 

107-98-2 1-Methoxy-2-propanol 1, 2, 3, 4 

2190-04-7 1-Octadecanamine, acetate (1:1) 8 

124-28-7 1-Octadecanamine, N,N-dimethyl 1, 3, 4 

112-88-9 1-Octadecene 3 

111-87-5 1-Octanol 1, 4 

71-41-0 1-Pentanol 8 

61789-39-7 

61789-40-0 

68139-30-0 

149879-98-1 

1-Propanaminium, 3-amino-N-(carboxymethyl)-N,Ndimethyl-, 

N-coco acyl derivs., chlorides, sodium salts 

1-Propanaminium, 3-amino-N-(carboxymethyl)-N,Ndimethyl-, 

N-coco acyl derivs., inner salts 

1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,Ndimethyl-3-sulfo-, 

N-coco acyl derivs., inner salts 

1-Propanaminium, N-(carboxymethyl)-N,N-dimethyl-3 

[[(13Z)-1-oxo-13-docosen-1-yl]amino]-, 

5284-66-2 1-Propanesulfonic acid 3 

 

4 

2, 4 

1 

1, 2, 3, 4 

1, 3, 4 

71-23-8 1-Propanol 1, 2, 4, 5 

23519-77-9 1-Propanol, zirconium(4+) salt 1, 4, 8 

115-07-1 1-Propene 2 

1120-36-1 1-Tetradecene 3 

112-70-9 1-Tridecanol 1, 4 

112-42-5 1-Undecanol 2 

112-34-5 2-(2-Butoxyethoxy)ethanol 2, 4 

111-90-0 2-(2-Ethoxyethoxy)ethanol 1, 4 

112-15-2 2-(2-Ethoxyethoxy)ethyl acetate 1, 4 

102-81-8 2-(Dibutylamino)ethanol 1, 4 

1, 3 


198




IUPAC 


Structure 

34375-28-5 2-(Hydroxymethylamino)ethanol 1, 4 

21564-17-0 2-(Thiocyanomethylthio)benzothiazole 2 

27776-21-2 

10213-78-2 2,2'-(Octadecylimino)diethanol 1 

929-59-9 2,2'-[Ethane-1,2-diylbis(oxy)]diethanamine 1, 4 

9003-11-6 2,2'-[propane-1,2-diylbis(oxy)]diethanol 1, 3, 4, 8 

25085-99-8 

2,2'-(Azobis(1-methylethylidene))bis(4,5-dihydro-1Himidazole)dihydrochloride 

2,2'-[propane-2,2-diylbis(4,1 

phenyleneoxymethylene)]dioxirane 

10222-01-2 2,2-Dibromo-3-nitrilopropionamide 

73003-80-2 2,2-Dibromopropanediamide 3 

24634-61-5 2,4-Hexadienoic acid, potassium salt, (2E,4E) 3 

915-67-3 

2,7-Naphthalenedisulfonic acid, 3-hydroxy-4-[2-(4-sulfo 

1-naphthalenyl) diazenyl] -, sodium salt (1:3) 

 

 

 

3 

1, 4, 8 

1, 2, 3, 4, 

6, 7, 8 

9002-93-1 2-[4-(1,1,3,3-tetramethylbutyl)phenoxy]ethanol 1, 3, 4 

NA 

2-Acrylamide - 2-propanesulfonic acid and N,Ndimethylacrylamide 

copolymer 

NA 2-acrylamido -2-methylpropanesulfonic acid copolymer 2 

15214-89-8 2-Acrylamido-2-methyl-1-propanesulfonic acid 1, 3 

124-68-5 2-Amino-2-methylpropan-1-ol 8 

2002-24-6 2-Aminoethanol hydrochloride 4, 8 

52-51-7 2-Bromo-2-nitropropane-1,3-diol 1, 2, 3, 4, 6 

1113-55-9 2-Bromo-3-nitrilopropionamide 1, 2, 3, 4, 5 

96-29-7 2-Butanone oxime 1 

143106-84-7 

68442-77-3 

2-Butanone, 4-[[[(1R,4aS,10aR)-1,2,3,4,4a,9,10,10a 

octahydro-1,4a-dimethyl-7-(1-methylethyl)-1 

phenanthrenyl]methyl](3-oxo-3-phenylpropyl)amino]-, 

hydrochloride (1:1) 

2-Butenediamide, (2E)-, N,N'-bis[2-(4,5-dihydro-2-nortalloil 

alkyl-1H-imidazol-1-yl)ethyl] derivs. 

111-76-2 2-Butoxyethanol 

110-80-5 2-Ethoxyethanol 6 

 

 

4 

2 

1, 4 

3, 8 

1, 2, 3, 4, 

6, 7, 8 

104-76-7 2-Ethyl-1-hexanol 1, 2, 3, 4, 5 

645-62-5 2-Ethyl-2-hexenal 2 

5444-75-7 2-Ethylhexyl benzoate 4 


199




IUPAC 


Structure 

818-61-1 2-Hydroxyethyl acrylate 1, 4 

13427-63-9 2-Hydroxyethylammonium hydrogen sulphite 1 

60-24-2 2-Mercaptoethanol 1, 4 

109-86-4 2-Methoxyethanol 4 

78-83-1 2-Methyl-1-propanol 1, 2, 4 

107-41-5 2-Methyl-2,4-pentanediol 1, 2, 4 

2682-20-4 2-Methyl-3(2H)-isothiazolone 1, 2, 4 

115-19-5 2-Methyl-3-butyn-2-ol 3 

78-78-4 2-Methylbutane 2 

62763-89-7 2-Methylquinoline hydrochloride 3 

37971-36-1 2-Phosphono-1,2,4-butanetricarboxylic acid 1, 4 

93858-78-7 

2-Phosphonobutane-1,2,4-tricarboxylic acid, potassium 

salt (1:x) 

1 

555-31-7 2-Propanol, aluminum salt 1 

26062-79-3 

2-Propen-1-aminium, N,N-dimethyl-N-2-propenyl-, 

chloride, homopolymer 

 

3 

13533-05-6 2-Propenoic acid, 2-(2-hydroxyethoxy)ethyl ester 4 

113221-69-5 

111560-38-4 

2-Propenoic acid, ethyl ester, polymer with ethenyl 

acetate and 2,5-furandione, hydrolyzed 

2-Propenoic acid, ethyl ester, polymer with ethenyl 

acetate and 2,5-furandione, hydrolyzed, sodium salt 

4, 8 

8 

9003-04-7 2-Propenoic acid, homopolymer, sodium salt 1, 2, 3, 4 

9003-06-9 2-Propenoic acid, polymer with 2-propenamide 4, 8 

25987-30-8 

37350-42-8 

151006-66-5 

2-Propenoic acid, polymer with 2-propenamide, sodium 

salt 

2-Propenoic acid, sodium salt (1:1), polymer with sodium 

2-methyl-2-((1-oxo-2-propen-1-yl)amino)-1 

propanesulfonate (1:1) 

2-Propenoic acid, telomer with sodium 4 

ethenylbenzenesulfonate (1:1), sodium 2-methyl-2-[(1 

oxo-2-propen-1-yl)amino]-1-propanesulfonate (1:1) and 

sodium sulfite (1:1), sodium salt 

1 

71050-62-9 2-Propenoic, polymer with sodium phosphinate 3, 4 

75673-43-7 3,4,4-Trimethyloxazolidine 8 

51229-78-8 

3,5,7-Triazatricyclo(3.3.1.1(superscript 3,7))decane, 1-(3 

chloro-2-propenyl)-, chloride, (Z) 

3, 4, 8 

4 

3 

5392-40-5 3,7-Dimethyl-2,6-octadienal 3 


200




IUPAC 


Structure 

104-55-2 3-Phenylprop-2-enal 1, 2, 3, 4, 7 

12068-08-5 4-(Dodecan-6-yl)benzenesulfonic acid – morpholine (1:1) 1, 4 

51200-87-4 4,4-Dimethyloxazolidine 8 

5877-42-9 4-Ethyloct-1-yn-3-ol 1, 2, 3, 4 

121-33-5 4-Hydroxy-3-methoxybenzaldehyde 3 

122-91-8 4-Methoxybenzyl formate 3 

150-76-5 4-Methoxyphenol 4 

108-11-2 4-Methyl-2-pentanol 1, 4 

108-10-1 4-Methyl-2-pentanone 5 

104-40-5 4-Nonylphenol 8 

26172-55-4 5-Chloro-2-methyl-3(2H)-isothiazolone 1, 2, 4 

106-22-9 6-Octen-1-ol, 3,7-dimethyl 3 

75-07-0 Acetaldehyde 1, 4 

64-19-7 Acetic acid 

1, 2, 3, 4, 

5, 6, 7, 8 

25213-24-5 Acetic acid ethenyl ester, polymer with ethenol 1, 4 

90438-79-2 Acetic acid, C6-8-branched alkyl esters 4 

68442-62-6 

Acetic acid, hydroxy-, reaction products with 

triethanolamine 

3 

5421-46-5 Acetic acid, mercapto-, monoammonium salt 2, 8 

108-24-7 Acetic anhydride 1, 2, 3, 4, 7 

67-64-1 Acetone 1, 3, 4, 6 

7327-60-8 Acetonitrile, 2,2',2''-nitrilotris 1, 4 

98-86-2 Acetophenone 1 

77-89-4 Acetyltriethyl citrate 1, 4 

107-02-8 Acrolein 2 

79-06-1 Acrylamide 1, 2, 3, 4 

25085-02-3 Acrylamide/ sodium acrylate copolymer 1, 2, 3, 4, 8 

38193-60-1 

Acrylamide-sodium-2-acrylamido-2-methlypropane 

sulfonate copolymer 

1, 2, 3, 4 

79-10-7 Acrylic acid 2, 4 

110224-99-2 

Acrylic acid, with sodium-2-acrylamido-2-methyl-1 

propanesulfonate and sodium phosphinate 

8 

67254-71-1 Alcohols, C10-12, ethoxylated 3 

68526-86-3 Alcohols, C11-14-iso-, C13-rich 3 


201




CASRN Chemical Name 

228414-35-5 Alcohols, C11-14-iso-, C13-rich, butoxylated ethoxylated 

78330-21-9 Alcohols, C11-14-iso-, C13-rich, ethoxylated 

126950-60-5 Alcohols, C12-14-secondary 

84133-50-6 Alcohols, C12-14-secondary, ethoxylated 


68603-25-8 Alcohols, C8-10, ethoxylated propoxylated 


93924-07-3 Alkanes, C10-14 

90622-52-9 Alkanes, C10-16-branched and linear 

68551-19-9 Alkanes, C12-14-iso 

68551-20-2 Alkanes, C13-16-iso 

64743-02-8 Alkenes, C>10 .alpha. 

68411-00-7 Alkenes, C>8 

68607-07-8 

Alkenes, C24-25 alpha-, polymers with maleic anhydride, 

docosyl esters 

71011-24-0 Alkyl quaternary ammonium with bentonite 

85409-23-0 

Alkyl* dimethyl ethylbenzyl ammonium chloride 

*(50%C12, 30%C14, 17%C16, 3%C18) 

42615-29-2 Alkylbenzenesulfonate, linear 

1302-62-1 Almandite and pyrope garnet 

60828-78-6 

alpha-[3.5-dimethyl-1-(2-methylpropyl)hexyl]-omegahydroxy-poly(oxy-1,2-ethandiyl) 

9000-90-2 alpha-Amylase 

98-55-5 Alpha-Terpineol 

1302-42-7 Aluminate (AlO 1- 2 ), sodium 

7429-90-5 Aluminum 

12042-68-1 Aluminum calcium oxide (Al 2 CaO 4 ) 

7446-70-0 Aluminum chloride 

1327-41-9 Aluminum chloride, basic 

1344-28-1 Aluminum oxide 

12068-56-3 Aluminum oxide silicate 

12141-46-7 Aluminum silicate 

10043-01-3 Aluminum sulfate 

68155-07-7 Amides, C8-18 and C18-unsatd., N,N-bis(hydroxyethyl) 

68140-01-2 Amides, coco, N-[3-(dimethylamino)propyl] 

IUPAC 

Name and Reference 

Structure 

1 

3, 4, 8 

1, 3, 4 

3, 4, 8 

2, 4, 8 

3 

1, 2, 4, 8 

1 

4 

2, 4, 8 

1, 4 

1, 3, 4, 8 

1 

8 

4 

8 

1, 4, 6 

1, 4 

3 

4 

3 

2, 4 

1, 4, 6 

2 

1, 4 

3, 4 

1, 2, 4 

1, 2, 4 

1, 2, 4 

1, 4 

3 

1, 4 


202




IUPAC 


Structure 

70851-07-9 

Amides, coco, N-[3-(dimethylamino)propyl], alkylation 

products with chloroacetic acid, sodium salts 

68155-09-9 Amides, coco, N-[3-(dimethylamino)propyl], N-oxides 1, 3, 4 

68876-82-4 Amides, from C16-22 fatty acids and diethylenetriamine 3 

68155-20-4 Amides, tall-oil fatty, N,N-bis(hydroxyethyl) 3, 4 

68647-77-8 Amides, tallow, N-[3-(dimethylamino)propyl],N-oxides 1, 4 

68155-39-5 Amines, C14-18; C16-18-unsaturated, alkyl, ethoxylated 1 

68037-94-5 Amines, C8-18 and C18-unsatd. alkyl 5 

61788-46-3 Amines, coco alkyl 4 

61790-57-6 Amines, coco alkyl, acetates 1, 4 

61788-93-0 Amines, coco alkyldimethyl 8 

61790-59-8 Amines, hydrogenated tallow alkyl, acetates 4 

68966-36-9 

68603-67-8 

Amines, polyethylenepoly-, ethoxylated, 

phosphonomethylated 

Amines, polyethylenepoly-, reaction products with benzyl 

chloride 

61790-33-8 Amines, tallow alkyl 8 

61791-26-2 Amines, tallow alkyl, ethoxylated 1, 3 

68551-33-7 Amines, tallow alkyl, ethoxylated, acetates (salts) 1, 3, 4 

68308-48-5 Amines, tallow alkyl, ethoxylated, phosphates 4 

6419-19-8 Aminotrimethylene phosphonic acid 1, 4, 8 

7664-41-7 Ammonia 1, 2, 3, 4, 7 

32612-48-9 Ammonium (lauryloxypolyethoxy)ethyl sulfate 4 

631-61-8 Ammonium acetate 1, 3, 4, 5, 8 

10604-69-0 Ammonium acrylate 8 

26100-47-0 Ammonium acrylate-acrylamide polymer 2, 4, 8 

7803-63-6 Ammonium bisulfate 2 

10192-30-0 Ammonium bisulfite 1, 2, 3, 4, 7 

12125-02-9 Ammonium chloride 

7632-50-0 Ammonium citrate (1:1) 3 

3012-65-5 Ammonium citrate (2:1) 8 

2235-54-3 Ammonium dodecyl sulfate 1 

 

1, 4 

1, 4 

1 

1, 2, 3, 4, 

5, 6, 8 

12125-01-8 Ammonium fluoride 1, 4 

1066-33-7 Ammonium hydrogen carbonate 1, 4 


203




IUPAC 


Structure 

1341-49-7 Ammonium hydrogen difluoride 1, 3, 4, 7 

13446-12-3 Ammonium hydrogen phosphonate 4 

1336-21-6 Ammonium hydroxide 1, 3, 4 

8061-53-8 Ammonium ligninsulfonate 2 

6484-52-2 Ammonium nitrate 1, 2, 3 

7722-76-1 Ammonium phosphate 1, 4 

7783-20-2 Ammonium sulfate 1, 2, 3, 4, 6 

99439-28-8 Amorphous silica 1, 7 

104-46-1 Anethole 3 

62-53-3 Aniline 2, 4 

1314-60-9 Antimony pentoxide 1, 4 

10025-91-9 Antimony trichloride 1, 4 

1309-64-4 Antimony trioxide 8 

7440-38-2 Arsenic 4 

68131-74-8 Ashes, residues 4 

68201-32-1 Asphalt, sulfonated, sodium salt 2 

12174-11-7 Attapulgite 2, 3 

31974-35-3 Aziridine, polymer with 2-methyloxirane 4, 8 

7727-43-7 Barium sulfate 1, 2, 4 

1318-16-7 Bauxite 1, 2, 4 

1302-78-9 Bentonite 1, 2, 4, 6 

121888-68-4 

Bentonite, benzyl(hydrogenated tallow alkyl) 

dimethylammonium stearate complex 

80-08-0 Benzamine, 4,4'-sulfonylbis 1, 4 

71-43-2 Benzene 1, 3, 4 

98-82-8 Benzene, (1-methylethyl) 1, 2, 3, 4 

119345-03-8 Benzene, 1,1'-oxybis-, tetrapropylene derivs., sulfonated 8 

119345-04-9 

Benzene, 1,1'-oxybis-, tetrapropylene derivs., sulfonated, 

sodium salts 

611-14-3 Benzene, 1-ethyl-2-methyl 4 

68648-87-3 Benzene, C10-16-alkyl derivs. 1 

9003-55-8 Benzene, ethenyl-, polymer with 1,3-butadiene 2, 4 

74153-51-8 

Benzenemethanaminium, N,N-dimethyl-N-(2-((1-oxo-2 

propen-1-yl)oxy)ethyl)-, chloride (1:1), polymer with 2 

propenamide 

98-11-3 Benzenesulfonic acid 2 

 

3, 4 

3, 4, 8 

3 


204




IUPAC 


Structure 

37953-05-2 Benzenesulfonic acid, (1-methylethyl)-, 4 

37475-88-0 Benzenesulfonic acid, (1-methylethyl)-, ammonium salt 3, 4 

28348-53-0 Benzenesulfonic acid, (1-methylethyl)-, sodium salt 8 

68584-22-5 Benzenesulfonic acid, C10-16-alkyl derivs. 1, 4 

255043-08-4 

68584-27-0 

90218-35-2 

Benzenesulfonic acid, C10-16-alkyl derivs., compds. with 

cyclohexylamine 

Benzenesulfonic acid, C10-16-alkyl derivs., potassium 

salts 

Benzenesulfonic acid, dodecyl-, branched, compds. with 

2-propanamine 

26264-06-2 Benzenesulfonic acid, dodecyl-, calcium salt 4 

68648-81-7 

Benzenesulfonic acid, mono-C10-16 alkyl derivs., 

compds. with 2-propanamine 

 

 

 

 

1 

1, 4, 8 

65-85-0 Benzoic acid 1, 4, 7 

100-44-7 Benzyl chloride 1, 2, 4, 8 

139-07-1 Benzyldimethyldodecylammonium chloride 2, 8 

122-18-9 Benzylhexadecyldimethylammonium chloride 8 

68425-61-6 

Bis(1-methylethyl)naphthalenesulfonic acid, 

cyclohexylamine salt 

111-44-4 Bis(2-chloroethyl) ether 8 

80-05-7 Bisphenol A 4 

65996-69-2 Blast furnace slag 2, 3 

1303-96-4 Borax 1, 2, 3, 4, 6 

10043-35-3 Boric acid 

 

4 

1, 4 

1 

1, 2, 3, 4, 

6, 7 

1303-86-2 Boric oxide 1, 2, 3, 4 

11128-29-3 Boron potassium oxide 1 

1330-43-4 Boron sodium oxide 1, 2, 4 

12179-04-3 Boron sodium oxide pentahydrate 8 

106-97-8 Butane 2, 5 

2373-38-8 

Butanedioic acid, sulfo-, 1,4-bis(1,3-dimethylbutyl) ester, 

sodium salt 

2673-22-5 Butanedioic acid, sulfo-, 1,4-ditridecyl ester, sodium salt 4 

2426-08-6 Butyl glycidyl ether 1, 4 

138-22-7 Butyl lactate 1, 4 

3734-67-6 C.I. Acid red 1 4 

 

1 


205




IUPAC 


Structure 

6625-46-3 C.I. Acid violet 12, disodium salt 4 

6410-41-9 C.I. Pigment Red 5 4 

4477-79-6 C.I. Solvent Red 26 4 

70592-80-2 C10-16-Alkyldimethylamines oxides 4 

68002-97-1 C10-C16 ethoxylated alcohol 1, 2, 3, 4, 8 

68131-40-8 C11-15-Secondary alcohols ethoxylated 1, 2, 8 

73138-27-9 C12-14 tert-alkyl ethoxylated amines 3 

66402-68-4 Calcined bauxite 2, 8 

12042-78-3 Calcium aluminate 2 

7789-41-5 Calcium bromide 4 

10043-52-4 Calcium chloride 1, 2, 3, 4, 7 

10035-04-8 Calcium dichloride dihydrate 1, 4 

7789-75-5 Calcium fluoride 1, 4 

1305-62-0 Calcium hydroxide 1, 2, 3, 4 

7778-54-3 Calcium hypochlorite 1, 2, 4 

58398-71-3 Calcium magnesium hydroxide oxide 4 

1305-78-8 Calcium oxide 1, 2, 4, 7 

1305-79-9 Calcium peroxide 1, 3, 4, 8 

7778-18-9 Calcium sulfate 1, 2, 4 

10101-41-4 Calcium sulfate dihydrate 2 

76-22-2 Camphor 3 

1333-86-4 Carbon black 1, 2, 4 

124-38-9 Carbon dioxide 1, 3, 4, 6 

471-34-1 Carbonic acid calcium salt (1:1) 1, 2, 4 

584-08-7 Carbonic acid, dipotassium salt 1, 2, 3, 4, 8 

39346-76-4 Carboxymethyl guar gum, sodium salt 1, 2, 4 

61791-12-6 Castor oil, ethoxylated 1, 3 

8000-27-9 Cedarwood oil 3 

9005-81-6 Cellophane 1, 4 

9012-54-8 Cellulase 1, 2, 3, 4, 5 

9004-34-6 Cellulose 1, 2, 3, 4 

9004-32-4 Cellulose, carboxymethyl ether, sodium salt 2, 3, 4 

16887-00-6 Chloride 4, 8 

7782-50-5 Chlorine 2 


206




IUPAC 


Structure 

10049-04-4 Chlorine dioxide 1, 2, 3, 4, 8 

78-73-9 Choline bicarbonate 3, 8 

67-48-1 Choline chloride 1, 3, 4, 7, 8 

16065-83-1 Chromium (III), insoluble salts 2, 6 

18540-29-9 Chromium (VI) 6 

39430-51-8 Chromium acetate, basic 2 

1066-30-4 Chromium(III) acetate 1, 2 

77-92-9 Citric acid 1, 2, 3, 4, 7 

8000-29-1 Citronella oil 3 

94266-47-4 Citrus extract 1, 3, 4, 8 

50815-10-6 Coal, granular 1, 2, 4 

71-48-7 Cobalt(II) acetate 1, 4 

68424-94-2 Coco-betaine 3 

68603-42-9 Coconut oil acid/Diethanolamine condensate (2:1) 1 

61789-18-2 Coconut trimethylammonium chloride 1, 8 

7440-50-8 Copper 1, 4 

7758-98-7 Copper sulfate 1, 4, 8 

7758-89-6 Copper(I) chloride 1, 4 

7681-65-4 Copper(I) iodide 1, 2, 4, 6 

7447-39-4 Copper(II) chloride 1, 3, 4 

68525-86-0 Corn flour 4 

11138-66-2 Corn sugar gum 1, 2, 4 

1302-74-5 Corundum (Aluminum oxide) 4, 8 

68308-87-2 Cottonseed, flour 2, 4 

91-64-5 Coumarin 3 

14464-46-1 Cristobalite 1, 2, 4 

15468-32-3 Crystalline silica, tridymite 1, 2, 4 

10125-13-0 Cupric chloride dihydrate 1, 4, 7 

110-82-7 Cyclohexane 1, 7 

108-94-1 Cyclohexanone 1, 4 

18472-87-2 D&C Red 28 4 

533-74-4 Dazomet 

1, 2, 3, 4, 

7, 8 

1120-24-7 Decyldimethylamine 3, 4 

7789-20-0 Deuterium oxide 8 


207




IUPAC 


Structure 

50-70-4 D-Glucitol 1, 3, 4 

526-95-4 D-Gluconic acid 1, 4 

3149-68-6 D-Glucopyranoside, methyl 2 

50-99-7 D-Glucose 1, 4 

117-81-7 Di(2-ethylhexyl) phthalate 1, 4 

7727-54-0 Diammonium peroxydisulfate 

68855-54-9 Diatomaceous earth 2, 4 

1, 2, 3, 4, 

6, 7, 8 

91053-39-3 Diatomaceous earth, calcined 1, 2, 4 

3252-43-5 Dibromoacetonitrile 1, 2, 3, 4, 8 

10034-77-2 Dicalcium silicate 1, 2, 4 

7173-51-5 Didecyldimethylammonium chloride 1, 2, 4, 8 

111-42-2 Diethanolamine 1, 2, 3, 4, 6 

25340-17-4 Diethylbenzene 1, 3, 4 

111-46-6 Diethylene glycol 1, 2, 3, 4, 7 

111-77-3 Diethylene glycol monomethyl ether 1, 2, 4 

111-40-0 Diethylenetriamine 1, 2, 4, 5 

68647-57-4 Diethylenetriamine reaction product with fatty acid dimers 2 

38640-62-9 Diisopropylnaphthalene 3, 4 

627-93-0 Dimethyl adipate 8 

1119-40-0 Dimethyl glutarate 1, 4 

63148-62-9 Dimethyl polysiloxane 1, 2, 4 

106-65-0 Dimethyl succinate 8 

108-01-0 Dimethylaminoethanol 2, 4 

7398-69-8 Dimethyldiallylammonium chloride 3, 4 

101-84-8 Diphenyl oxide 3 

7758-11-4 Dipotassium monohydrogen phosphate 5 

25265-71-8 Dipropylene glycol 1, 3, 4 

31291-60-8 Di-sec-butylphenol 1 

28519-02-0 

Disodium 

dodecyl(sulphonatophenoxy)benzenesulphonate 

38011-25-5 Disodium ethylenediaminediacetate 1, 4 

6381-92-6 Disodium ethylenediaminetetraacetate dihydrate 1 

12008-41-2 Disodium octaborate 4, 8 

12280-03-4 Disodium octaborate tetrahydrate 1, 4 

 

1 


208




IUPAC 


Structure 

68477-31-6 

68333-25-5 

Distillates, petroleum, catalytic reformer fractionator 

residue, low-boiling 

Distillates, petroleum, hydrodesulfurized light catalytic 

cracked 

64742-80-9 Distillates, petroleum, hydrodesulfurized middle 1 

64742-52-5 Distillates, petroleum, hydrotreated heavy naphthenic 1, 2, 3, 4 

64742-54-7 Distillates, petroleum, hydrotreated heavy paraffinic 1, 2, 4 

64742-47-8 Distillates, petroleum, hydrotreated light 

1, 4 

1 

1, 2, 3, 4, 

5, 7, 8 

64742-53-6 Distillates, petroleum, hydrotreated light naphthenic 1, 2, 8 

64742-55-8 Distillates, petroleum, hydrotreated light paraffinic 8 

64742-46-7 Distillates, petroleum, hydrotreated middle 1, 2, 3, 4, 8 

64741-59-9 Distillates, petroleum, light catalytic cracked 1, 4 

64741-77-1 Distillates, petroleum, light hydrocracked 3 

64742-65-0 Distillates, petroleum, solvent-dewaxed heavy paraffinic 1 

64741-96-4 Distillates, petroleum, solvent-refined heavy naphthenic 1, 4 

64742-91-2 Distillates, petroleum, steam-cracked 1, 4 

64741-44-2 Distillates, petroleum, straight-run middle 1, 2, 4 

64741-86-2 Distillates, petroleum, sweetened middle 1, 4 

71011-04-6 Ditallow alkyl ethoxylated amines 3 

10326-41-7 D-Lactic acid 1, 4 

5989-27-5 D-Limonene 

577-11-7 Docusate sodium 1 

112-40-3 Dodecane 8 

123-01-3 Dodecylbenzene 3, 4 

1, 3, 4, 5, 

7, 8 

27176-87-0 Dodecylbenzene sulfonic acid 2, 3, 4, 8 

26836-07-7 Dodecylbenzenesulfonic acid, monoethanolamine salt 1, 4 

12276-01-6 EDTA, copper salt 1, 5, 6 

37288-54-3 Endo-1,4-.beta.-mannanase. 3, 8 

106-89-8 Epichlorohydrin 1, 4, 8 

44992-01-0 

69418-26-4 

Ethanaminium, N,N,N-trimethyl-2-[(1-oxo-2 

propenyl)oxy]-, chloride 

Ethanaminium, N,N,N-trimethyl-2-[(1-oxo-2 

propenyl)oxy]-, chloride, polymer with 2-propenamide 

3 

1, 3, 4 


209




CASRN 

Chemical Name 

Ethanaminium, N,N,N-trimethyl-2[(2-methyl-1-oxo-2 

26006-22-4 propen-1-yl0oxy]-, methyl sulfate 91:1), polymer with 2 

propenamide 

27103-90-8 

74-84-0 Ethane 

64-17-5 Ethanol 

68171-29-9 

Ethanaminium, N,N,N-trimethyl-2-[(2-methyl-1-oxo-2 

propenyl)oxy]-, methyl sulfate, homopolymer 

Ethanol, 2,2',2''-nitrilotris-, tris(dihydrogen phosphate) 

(ester), sodium salt 

61791-47-7 Ethanol, 2,2'-iminobis-, N-coco alkyl derivs., N-oxides 

61791-44-4 Ethanol, 2,2'-iminobis-, N-tallow alkyl derivs. 

68909-77-3 

68877-16-7 

Ethanol, 2,2'-oxybis-, reaction products with ammonia, 

morpholine derivs. residues 

Ethanol, 2,2-oxybis-, reaction products with ammonia, 

morpholine derivs. residues, acetates (salts) 

Ethanol, 2,2-oxybis-, reaction products with ammonia, 

102424-23-7 morpholine derivs. residues, reaction products with sulfur 

dioxide 

25446-78-0 

Ethanol, 2-[2-[2-(tridecyloxy)ethoxy]ethoxy]-, hydrogen 

sulfate, sodium salt 

34411-42-2 Ethanol, 2-amino-, polymer with formaldehyde 

68649-44-5 

141-43-5 Ethanolamine 

Ethanol, 2-amino-, reaction products with ammonia, byproducts 

from, phosphonomethylated 

66455-15-0 Ethoxylated C10-14 alcohols 








9002-92-0 Ethoxylated dodecyl alcohol 

61790-82-7 Ethoxylated hydrogenated tallow alkylamines 

68439-51-0 Ethoxylated propoxylated C12-14 alcohols 

52624-57-4 Ethoxylated, propoxylated trimethylolpropane 

141-78-6 Ethyl acetate 

IUPAC 

Name and 

Structure 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reference 

1, 4 

8 

2, 5 

1, 2, 3, 4, 

5, 6, 8 

4 

1 

1 

4, 8 

4 

4 

1, 4 

4 

4 

1, 2, 3, 4, 6 

3 

4 

2, 3, 4, 8 

3, 4 

3, 4, 8 

3, 4, 8 

3, 4, 8 

3, 4 

4 

4 

1, 3, 4, 8 

3 

1, 4, 7 


210




IUPAC 


Structure 

141-97-9 Ethyl acetoacetate 1, 4 

93-89-0 Ethyl benzoate 3 

97-64-3 Ethyl lactate 3 

118-61-6 Ethyl salicylate 3 

100-41-4 Ethylbenzene 1, 2, 3, 4, 7 

9004-57-3 Ethylcellulose 2 

107-21-1 Ethylene glycol 

1, 2, 3, 4, 

6, 7, 8 

75-21-8 Ethylene oxide 1, 2, 3, 4 

107-15-3 Ethylenediamine 2, 4 

60-00-4 Ethylenediaminetetraacetic acid 1, 2, 4 

64-02-8 Ethylenediaminetetraacetic acid tetrasodium salt 1, 2, 3, 4 

67989-88-2 

Ethylenediaminetetraacetic acid, diammonium copper 

salt 

139-33-3 Ethylenediaminetetraacetic acid, disodium salt 1, 3, 4, 8 

74-86-2 Ethyne 7 

68604-35-3 

Fatty acids, C 8-18 and C18-unsaturated compounds 

with diethanolamine 

70321-73-2 Fatty acids, C14-18 and C16-18-unsatd., distn. residues 2 

61788-89-4 Fatty acids, C18-unsatd., dimers 2 

61791-29-5 Fatty acids, coco, ethoxylated 3 

61791-08-0 

Fatty acids, coco, reaction products with ethanolamine, 

ethoxylated 

61790-90-7 Fatty acids, tall oil, hexa esters with sorbitol, ethoxylated 1, 4 

68188-40-9 

Fatty acids, tall oil, reaction products with acetophenone, 

formaldehyde and thiourea 

61790-12-3 Fatty acids, tall-oil 1, 2, 3, 4 

61790-69-0 

Fatty acids, tall-oil, reaction products with 

diethylenetriamine 

8052-48-0 Fatty acids, tallow, sodium salts 1, 3 

68153-72-0 

Fatty acids, vegetable-oil, reaction products with 

diethylenetriamine 

3844-45-9 FD&C Blue no. 1 1, 4 

7705-08-0 Ferric chloride 1, 3, 4 

10028-22-5 Ferric sulfate 1, 4 

17375-41-6 Ferrous sulfate monohydrate 2 

 

4 

3 

3 

3 

1, 4 

3 


211




IUPAC 


Structure 

65997-17-3 Fiberglass 2, 3, 4 

50-00-0 Formaldehyde 1, 2, 3, 4 

NA Formaldehyde amine 8 

29316-47-0 

63428-92-2 

28906-96-9 

30704-64-4 

Formaldehyde polymer with 4,1,1-(dimethylethyl)phenol 

and methyloxirane 

Formaldehyde polymer with methyl oxirane, 4 

nonylphenol and oxirane 

Formaldehyde, polymer with 2-(chloromethyl)oxirane and 

4,4'-(1-methylethylidene)bis[phenol] 

Formaldehyde, polymer with 4-(1,1-dimethylethyl)phenol, 

2-methyloxirane and oxirane 

 

 

 

 

3 

4, 8 

1, 4 

30846-35-6 Formaldehyde, polymer with 4-nonylphenol and oxirane 1, 4 

35297-54-2 Formaldehyde, polymer with ammonia and phenol 1, 4 

25085-75-0 Formaldehyde, polymer with bisphenol A 4 

70750-07-1 

Formaldehyde, polymer with N1-(2-aminoethyl)-1,2 

ethanediamine, benzylated 

55845-06-2 Formaldehyde, polymer with nonylphenol and oxirane 4 

153795-76-7 

Formaldehyde, polymers with branched 4-nonylphenol, 

ethylene oxide and propylene oxide 

 

 

1, 2, 4, 8 

75-12-7 Formamide 1, 2, 3, 4 

64-18-6 Formic acid 

8 

1, 3 

1, 2, 3, 4, 

6, 7 

590-29-4 Formic acid, potassium salt 1, 3, 4 

68476-30-2 Fuel oil, no. 2 1, 2 

68334-30-5 Fuels, diesel 2 

68476-34-6 Fuels, diesel, no. 2 2, 4, 8 

8031-18-3 Fuller's earth 2 

110-17-8 Fumaric acid 1, 2, 3, 4, 6 

98-01-1 Furfural 1, 4 

98-00-0 Furfuryl alcohol 1, 4 

64741-43-1 Gas oils, petroleum, straight-run 1, 4 

9000-70-8 Gelatin 1, 4 

12002-43-6 Gilsonite 1, 2, 4 

133-42-6 Gluconic acid 7 

111-30-8 Glutaraldehyde 1, 2, 3, 4, 7 

56-81-5 Glycerin, natural 1, 2, 3, 4, 5 


212




IUPAC 


Structure 

135-37-5 

Glycine, N-(carboxymethyl)-N-(2-hydroxyethyl)-, 

disodium salt 

150-25-4 Glycine, N,N-bis(2-hydroxyethyl) 1, 4 

5064-31-3 Glycine, N,N-bis(carboxymethyl)-, trisodium salt 1, 2, 3, 4 

139-89-9 

Glycine, N-[2-[bis(carboxymethyl)amino]ethyl]-N-(2 

hydroxyethyl)-, trisodium salt 

79-14-1 Glycolic acid 1, 3, 4 

2836-32-0 Glycolic acid sodium salt 1, 3, 4 

107-22-2 Glyoxal 1, 2, 4 

298-12-4 Glyoxylic acid 1 

9000-30-0 Guar gum 

68130-15-4 

Guar gum, carboxymethyl 2-hydroxypropyl ether, sodium 

salt 

13397-24-5 Gypsum 2, 4 

67891-79-6 Heavy aromatic distillate 1, 4 

 

 

1 

1 

1, 2, 3, 4, 

7, 8 

1, 2, 3, 4, 7 

1317-60-8 Hematite 1, 2, 4 

9025-56-3 Hemicellulase enzyme concentrate 3, 4 

142-82-5 Heptane 1, 2 

68526-88-5 Heptene, hydroformylation products, high-boiling 1, 4 

57-09-0 Hexadecyltrimethylammonium bromide 1 

110-54-3 Hexane 5 

124-04-9 Hexanedioic acid 1, 2, 4, 6 

1415-93-6 Humic acids, commercial grade 2 

68956-56-9 Hydrocarbons, terpene processing by-products 1, 3, 4 

7647-01-0 Hydrochloric acid 

1, 2, 3, 4, 

5, 6, 7, 8 

7664-39-3 Hydrogen fluoride 1, 2, 4 

7722-84-1 Hydrogen peroxide 1, 3, 4 

7783-06-4 Hydrogen sulfide 1, 2 

9004-62-0 Hydroxyethylcellulose 1, 2, 3, 4 

4719-04-4 Hydroxylamine hydrochloride 1, 3, 4 

10039-54-0 Hydroxylamine sulfate (2:1) 4 

9004-64-2 Hydroxypropyl cellulose 2, 4 

39421-75-5 Hydroxypropyl guar gum 

1, 3, 4, 5, 

6, 8 


213




IUPAC 


Structure 

120-72-9 Indole 2 

430439-54-6 Inulin, carboxymethyl ether, sodium salt 1, 4 

12030-49-8 Iridium oxide 8 

7439-89-6 Iron 2, 4 

1317-61-9 Iron oxide (Fe3O4) 4 

1332-37-2 Iron(II) oxide 1, 4 

7720-78-7 Iron(II) sulfate 2 

7782-63-0 Iron(II) sulfate heptahydrate 1, 2, 3, 4 

1309-37-1 Iron(III) oxide 1, 2, 4 

89-65-6 Isoascorbic acid 1, 3, 4 

75-28-5 Isobutane 2 

26952-21-6 Isooctanol 1, 4, 5 

123-51-3 Isopentyl alcohol 1, 4 

67-63-0 Isopropanol 

1, 2, 3, 4, 

6, 7 

42504-46-1 Isopropanolamine dodecylbenzenesulfonate 1, 3, 4 

75-31-0 Isopropylamine 1, 4 

68909-80-8 

Isoquinoline, reaction products with benzyl chloride and 

quinoline 

35674-56-7 Isoquinolinium, 2-(phenylmethyl)-, chloride 3 

9043-30-5 Isotridecanol, ethoxylated 1, 3, 4, 8 

1332-58-7 Kaolin 1, 2, 4 

8008-20-6 Kerosine (petroleum) 1, 2, 3, 4, 8 

64742-81-0 Kerosine, petroleum, hydrodesulfurized 1, 2, 4 

61790-53-2 Kieselguhr 1, 2, 4 

1302-76-7 Kyanite 1, 2, 4 

50-21-5 Lactic acid 1, 4, 8 

63-42-3 Lactose 3 

13197-76-7 Lauryl hydroxysultaine 1 

8022-15-9 Lavandula hybrida abrial herb oil 3 

4511-42-6 L-Dilactide 1, 4 

7439-92-1 Lead 1, 4 

8002-43-5 Lecithin 4 

129521-66-0 Lignite 2 

8062-15-5 Lignosulfuric acid 2 

 

3 


214




IUPAC 


Structure 

1317-65-3 Limestone 1, 2, 3, 4 

8001-26-1 Linseed oil 8 

79-33-4 L-Lactic acid 1, 4, 8 

546-93-0 Magnesium carbonate (1:1) 1, 3, 4 

7786-30-3 Magnesium chloride 1, 2, 4 

7791-18-6 Magnesium chloride hexahydrate 4 

1309-42-8 Magnesium hydroxide 1, 4 

19086-72-7 Magnesium iron silicate 1, 4 

10377-60-3 Magnesium nitrate 1, 2, 4 

1309-48-4 Magnesium oxide 1, 2, 3, 4 

14452-57-4 Magnesium peroxide 1, 4 

12057-74-8 Magnesium phosphide 1 

1343-88-0 Magnesium silicate 1, 4 

26099-09-2 Maleic acid homopolymer 8 

25988-97-0 

Methanamine-N-methyl polymer with chloromethyl 

oxirane 

74-82-8 Methane 2, 5 

67-56-1 Methanol 

 

4 

1, 2, 3, 4, 

5, 6, 7, 8 

100-97-0 Methenamine 1, 2, 4 

625-45-6 Methoxyacetic acid 8 

9004-67-5 Methyl cellulose 8 

119-36-8 Methyl salicylate 1, 2, 3, 4, 7 

78-94-4 Methyl vinyl ketone 1, 4 

108-87-2 Methylcyclohexane 1 

6317-18-6 Methylene bis(thiocyanate) 2 

66204-44-2 Methylenebis(5-methyloxazolidine) 2 

68891-11-2 

Methyloxirane polymer with oxirane, mono (nonylphenol) 

ether, branched 

12001-26-2 Mica 1, 2, 4, 6 

8012-95-1 Mineral oil - includes paraffin oil 4, 8 

64475-85-0 Mineral spirits 2 

26038-87-9 Monoethanolamine borate (1:x) 1, 4 

1318-93-0 Montmorillonite 2 

110-91-8 Morpholine 1, 2, 4 

 

3 


215




IUPAC 


Structure 

78-21-7 Morpholinium, 4-ethyl-4-hexadecyl-, ethyl sulfate 8 

1302-93-8 Mullite 1,2, 4, 8 

46830-22-2 

54076-97-0 

19277-88-4 

N-(2-Acryloyloxyethyl)-N-benzyl-N,N-dimethylammonium 

chloride 

N,N,N-Trimethyl-2[1-oxo-2-propenyl]oxy ethanaminimum 

chloride, homopolymer 

N,N,N-Trimethyl-3-((1-oxooctadecyl)amino)-1 

propanaminium methyl sulfate 

112-03-8 N,N,N-Trimethyloctadecan-1-aminium chloride 1, 3, 4 

109-46-6 N,N'-Dibutylthiourea 1, 4 

2605-79-0 N,N-Dimethyldecylamine oxide 1, 3, 4 

68-12-2 N,N-Dimethylformamide 1, 2, 4, 5, 8 

593-81-7 N,N-Dimethylmethanamine hydrochloride 1, 4, 5, 7 

1184-78-7 N,N-Dimethyl-methanamine-N-oxide 3 

1613-17-8 N,N-Dimethyloctadecylamine hydrochloride 1, 4 

110-26-9 N,N'-Methylenebisacrylamide 1, 4 

64741-68-0 Naphtha, petroleum, heavy catalytic reformed 1, 2, 3, 4 

64742-48-9 Naphtha, petroleum, hydrotreated heavy 1, 2, 3, 4, 8 

91-20-3 Naphthalene 

93-18-5 Naphthalene, 2-ethoxy 3 

 

 

 

3 

3 

1 

1, 2, 3, 4, 

5, 7 

28757-00-8 Naphthalenesulfonic acid, bis(1-methylethyl)- 1, 3, 4 

99811-86-6 

Naphthalenesulphonic acid, bis (1-methylethyl)-methyl 

derivatives 

68410-62-8 Naphthenic acid ethoxylate 4 

7786-81-4 Nickel sulfate 2 

10101-97-0 Nickel(II) sulfate hexahydrate 1, 4 

61790-29-2 Nitriles, tallow, hydrogenated 4 

4862-18-4 Nitrilotriacetamide 1, 4, 7 

139-13-9 Nitrilotriacetic acid 1, 4 

18662-53-8 Nitrilotriacetic acid trisodium monohydrate 1, 4 

7727-37-9 Nitrogen 1, 2, 3, 4, 6 

872-50-4 N-Methyl-2-pyrrolidone 1, 4 

105-59-9 N-Methyldiethanolamine 2, 4, 8 

109-83-1 N-Methylethanolamine 4 

68213-98-9 N-Methyl-N-hydroxyethyl-N-hydroxyethoxyethylamine 4 

 

1 


216




IUPAC 


Structure 

13127-82-7 N-Oleyl diethanolamide 1, 4 

25154-52-3 Nonylphenol (mixed) 1, 4 

8000-48-4 Oil of eucalyptus 3 

8007-02-1 Oil of lemongrass 3 

8000-25-7 Oil of rosemary 3 

112-80-1 Oleic acid 2, 4 

1317-71-1 Olivine 4 

8028-48-6 Orange terpenes 4 

68649-29-6 

51838-31-4 

Oxirane, methyl-, polymer with oxirane, mono-C10-16 

alkyl ethers, phosphates 

Oxiranemethanaminium, N,N,N-trimethyl-, chloride, 

homopolymer 

7782-44-7 Oxygen 4 

10028-15-6 Ozone 8 

8002-74-2 Paraffin waxes and Hydrocarbon waxes 1 

30525-89-4 Paraformaldehyde 2 

4067-16-7 Pentaethylenehexamine 4 

109-66-0 Pentane 2, 5 

628-63-7 Pentyl acetate 3 

540-18-1 Pentyl butyrate 3 

79-21-0 Peracetic acid 8 

93763-70-3 Perlite 4 

64743-01-7 Petrolatum, petroleum, oxidized 3 

8002-05-9 Petroleum 1, 2 

6742-47-8 Petroleum distillate hydrotreated light 8 

85-01-8 Phenanthrene 6 

 

1, 4 

1, 2, 3, 4, 

5, 8 

108-95-2 Phenol 1, 2, 4 

25068-38-6 

Phenol, 4,4'-(1-methylethylidene)bis-, polymer with 2 

(chloromethyl)oxirane 

1, 2, 4 

9003-35-4 Phenol, polymer with formaldehyde 1, 2, 4, 7 

7803-51-2 Phosphine 1, 4 

13598-36-2 Phosphonic acid 1, 4 

29712-30-9 Phosphonic acid (dimethylamino(methylene)) 1 

129828-36-0 

Phosphonic acid, (((2-[(2 

hydroxyethyl)(phosphonomethyl)amino)ethyl)imino]bis(m 

ethylene))bis-, compd. with 2-aminoethanol 

1 


217




IUPAC 


Structure 

67953-76-8 

3794-83-0 

15827-60-8 

70714-66-8 

22042-96-2 

34690-00-1 

Phosphonic acid, (1-hydroxyethylidene)bis-, potassium 

salt 

Phosphonic acid, (1-hydroxyethylidene)bis-, tetrasodium 

salt 

Phosphonic acid, [[(phosphonomethyl)imino]bis[2,1 

ethanediylnitrilobis(methylene)]]tetrakis- 


ethanediylnitrilobis(methylene)]]tetrakis-, ammonium salt 

(1:x) 


ethanediylnitrilobis(methylene)]]tetrakis-, sodium salt 


hexanediylnitrilobis(methylene)]]tetrakis 

 

 

 

 

 

 

4 

1, 4 

1, 2, 4 

3 

3 

1, 4, 8 

7664-38-2 Phosphoric acid 1, 2, 4 

7785-88-8 Phosphoric acid, aluminium sodium salt 1, 2 

7783-28-0 Phosphoric acid, diammonium salt 2 

68412-60-2 Phosphoric acid, mixed decyl and Et and octyl esters 1 

10294-56-1 Phosphorous acid 1 

85-44-9 Phthalic anhydride 1, 4 

8002-09-3 Pine oils 1, 2, 4 

25038-54-4 Policapram (Nylon 6) 1, 4 

62649-23-4 Poly (acrylamide-co-acrylic acid), partial sodium salt 3, 4 

26680-10-4 Poly(lactide) 1 

9014-93-1 

9016-45-9 

51811-79-1 

68987-90-6 

26635-93-8 

9004-96-0 

68891-38-3 

Poly(oxy-1,2-ethanediyl), .alpha.-(dinonylphenyl)-. 

omega.-hydroxy 

Poly(oxy-1,2-ethanediyl), .alpha.-(nonylphenyl)-.omega. 

hydroxy 

Poly(oxy-1,2-ethanediyl), .alpha.-(nonylphenyl)-.omega. 

hydroxy-, phosphate 

Poly(oxy-1,2-ethanediyl), .alpha.-(octylphenyl)-.omega. 

hydroxy-, branched 

Poly(oxy-1,2-ethanediyl), .alpha.,.alpha.'-[[(9Z)-9 

octadecenylimino]di-2,1-ethanediyl]bis[.omega.-hydroxy 

Poly(oxy-1,2-ethanediyl), .alpha.-[(9Z)-1-oxo-9 

octadecenyl]-.omega.-hydroxy 

Poly(oxy-1,2-ethanediyl), .alpha.-sulfo-.omega.-hydroxy-, 

C12-14-alkyl ethers, sodium salts 

 

 

 

 

 

 

 

4 

1, 2, 3, 4, 8 

1, 4 

1, 4 

1, 4 

8 

1, 4 


218




IUPAC 


Structure 

61723-83-9 

68015-67-8 

68412-53-3 

Poly(oxy-1,2-ethanediyl), a-hydro-w-hydroxy-, ether with 

D-glucitol (2:1), tetra-(9Z)-9-octadecenoate 

Poly(oxy-1,2-ethanediyl), alpha-(2,3,4,5 

tetramethylnonyl)-omega-hydroxy 

Poly(oxy-1,2-ethanediyl), alpha-(nonylphenyl)-omegahydroxy-,branched, 

phosphates 

8 

1 

1 

31726-34-8 Poly(oxy-1,2-ethanediyl), alpha-hexyl-omega-hydroxy 3, 8 

56449-46-8 

65545-80-4 

27306-78-1 

52286-19-8 

63428-86-4 

68037-05-8 

9081-17-8 

52286-18-7 

68890-88-0 

Poly(oxy-1,2-ethanediyl), alpha-hydro-omega-hydroxy-, 

(9Z)-9-octadecenoate 

Poly(oxy-1,2-ethanediyl), alpha-hydro-omega-hydroxy-, 

ether with alpha-fluoro-omega-(2 

hydroxyethyl)poly(difluoromethylene) (1:1) 

Poly(oxy-1,2-ethanediyl), alpha-methyl-omega-(3 

(1,3,3,3-tetramethyl-1-((trimethylsilyl)oxy)-1 

disiloxanyl)propoxy) 

Poly(oxy-1,2-ethanediyl), alpha-sulfo-omega-(decyloxy)-, 

ammonium salt (1:1) 

Poly(oxy-1,2-ethanediyl), alpha-sulfo-omega-(hexyloxy)-, 


Poly(oxy-1,2-ethanediyl), alpha-sulfo-omega-(hexyloxy)-, 

C6-10-alkyl ethers, ammonium salts 

Poly(oxy-1,2-ethanediyl), alpha-sulfo-omega- 

(nonylphenoxy) 

Poly(oxy-1,2-ethanediyl), alpha-sulfo-omega-(octyloxy) -, 


Poly(oxy-1,2-ethanediyl), alpha-sulfo-omega-hydroxy-, 

C10-12-alkyl ethers, ammonium salts 

 

 

 

 

 

3 

1 

1 

4 

1, 3, 4 

3, 4 

4 

4 

8 

24938-91-8 Poly(oxy-1,2-ethanediyl), alpha-tridecyl-omega-hydroxy 1, 3, 4 

127036-24-2 

68412-54-4 

Poly(oxy-1,2-ethanediyl), alpha-undecyl-omega-hydroxy-, 

branched and linear 

1 

2, 3, 4 

34398-01-1 Poly-(oxy-1,2-ethanediyl)-alpha-undecyl-omega-hydroxy 1, 3, 4, 8 

127087-87-0 Poly(oxy-1,2-ethanediyl)-nonylphenyl-hydroxy branched 1, 2, 3, 4 

25704-18-1 Poly(sodium-p-styrenesulfonate) 1, 4 

32131-17-2 

Poly(oxy-1,2-ethanediyl),alpha-(4-nonylphenyl)-omegahydroxy-,branched 

Poly[imino(1,6-dioxo-1,6-hexanediyl)imino-1,6 

hexanediyl] 

2 

9003-05-8 Polyacrylamide 1, 2, 4, 6 


219




IUPAC 


Structure 

NA Polyacrylate/ polyacrylamide blend 2 

66019-18-9 Polyacrylic acid, sodium bisulfite terminated 3 

25322-68-3 Polyethylene glycol 

9004-98-2 Polyethylene glycol (9Z)-9-octadecenyl ether 8 

68187-85-9 Polyethylene glycol ester with tall oil fatty acid 1 

1, 2, 3, 4, 

7, 8 

9036-19-5 Polyethylene glycol mono(octylphenyl) ether 1, 2, 3, 4, 8 

9004-77-7 Polyethylene glycol monobutyl ether 1, 4 

68891-29-2 

Polyethylene glycol mono-C8-10-alkyl ether sulfate 

ammonium 

 

1, 3, 4 

9046-01-9 Polyethylene glycol tridecyl ether phosphate 1, 3, 4 

9002-98-6 Polyethyleneimine 4 

25618-55-7 Polyglycerol 2 

9005-70-3 Polyoxyethylene sorbitan trioleate 3 

26027-38-3 Polyoxyethylene(10)nonylphenyl ether 1, 2, 3, 4, 8 

9046-10-0 Polyoxypropylenediamine 1 

68131-72-6 

Polyphosphoric acids, esters with triethanolamine, 

sodium salts 

68915-31-1 Polyphosphoric acids, sodium salts 1, 4 

25322-69-4 Polypropylene glycol 1, 2, 4 

68683-13-6 

Polypropylene glycol glycerol triether, epichlorohydrin, 

bisphenol A polymer 

9011-19-2 Polysiloxane 4 

9005-64-5 Polysorbate 20 8 

9003-20-7 Polyvinyl acetate copolymer 2 

9002-89-5 Polyvinyl alcohol 1, 2, 4 

NA Polyvinyl alcohol/polyvinyl acetate copolymer 1 

9002-85-1 Polyvinylidene chloride 8 

65997-15-1 Portland cement 2, 4 

127-08-2 Potassium acetate 1, 3, 4 

1327-44-2 Potassium aluminum silicate 5 

29638-69-5 Potassium antimonate 1, 4 

12712-38-8 Potassium borate 3 

20786-60-1 Potassium borate (1:x) 1, 3 

6381-79-9 Potassium carbonate sesquihydrate 5 

1 

1 


220




IUPAC 


Structure 

7447-40-7 Potassium chloride 

7778-50-9 Potassium dichromate 4 

1, 2, 3, 4, 

5, 6, 7 

1310-58-3 Potassium hydroxide 1, 2, 3, 4, 6 

7681-11-0 Potassium iodide 1, 4 

13709-94-9 Potassium metaborate 1, 2, 3, 4, 8 

143-18-0 Potassium oleate 4 

12136-45-7 Potassium oxide 1, 4 

7727-21-1 Potassium persulfate 1, 2, 4 

7778-80-5 Potassium sulfate 2 

74-98-6 Propane 2, 5 

2997-92-4 

Propanimidamide,2,2’' -aAzobis[(2-methyl-, 

amidinopropane) dihydrochloride 

1, 4 

34590-94-8 Propanol, 1(or 2)-(2-methoxymethylethoxy) 1, 2, 3, 4 

107-19-7 Propargyl alcohol 

108-32-7 Propylene carbonate 1, 4 

15220-87-8 Propylene pentamer 1 

106-42-3 p-Xylene 1, 4 

68391-11-7 Pyridine, alkyl derivs. 1, 4 

100765-57-9 Pyridinium, 1-(phenylmethyl)-, alkyl derivs., chlorides 4, 8 

70914-44-2 

Pyridinium, 1-(phenylmethyl)-, C7-8-alkyl derivs., 

chlorides 

6 

289-95-2 Pyrimidine 2 

109-97-7 Pyrrole 2 

14808-60-7 Quartz 

308074-31-9 

68607-28-3 

68153-30-0 

68989-00-4 

Quaternary ammonium compounds (2-ethylhexyl) 

hydrogenated tallow alkyl)dimethyl, methyl sulfates 

Quaternary ammonium compounds, (oxydi-2,1 

ethanediyl)bis[coco alkyldimethyl, dichlorides 

Quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, salts with 

bentonite 

Quaternary ammonium compounds, benzyl-C10-16 

alkyldimethyl, chlorides 

1, 2, 3, 4, 

5, 6, 7, 8 

1, 2, 3, 4, 

5, 6, 8 

8 

2, 3, 4, 8 

2, 5, 6 

1, 4 


221




IUPAC 


Structure 

68424-85-1 

68391-01-5 

61789-68-2 

68953-58-2 

71011-27-3 

68424-95-3 

61789-77-3 

68607-29-4 

8030-78-2 


alkyldimethyl, chlorides 


alkyldimethyl, chlorides 

Quaternary ammonium compounds, benzylcoco 

alkylbis(hydroxyethyl), chlorides 

Quaternary ammonium compounds, bis(hydrogenated 

tallow alkyl)dimethyl, salts with bentonite 

Quaternary ammonium compounds, bis(hydrogenated 

tallow alkyl)dimethyl, salts with hectorite 

Quaternary ammonium compounds, di-C8-10 

alkyldimethyl, chlorides 

Quaternary ammonium compounds, dicoco alkyldimethyl, 

chlorides 

Quaternary ammonium compounds, pentamethyltallow 

alkyltrimethylenedi-, dichlorides 

Quaternary ammonium compounds, trimethyltallow alkyl, 

chlorides 

 

1, 2, 4, 8 

8 

1, 4 

2, 3, 4, 8 

2 

2 

91-22-5 Quinoline 2, 4 

68514-29-4 Raffinates (petroleum) 5 

64741-85-1 Raffinates, petroleum, sorption process 1, 2, 4, 8 

64742-01-4 Residual oils, petroleum, solvent-refined 5 

64741-67-9 Residues, petroleum, catalytic reformer fractionator 1, 4, 8 

81-88-9 Rhodamine B 4 

8050-09-7 Rosin 1, 4 

12060-08-1 Scandium oxide 8 

63800-37-3 Sepiolite 2 

68611-44-9 Silane, dichlorodimethyl-, reaction products with silica 2 

7631-86-9 Silica 1, 2, 3, 4, 8 

112926-00-8 Silica gel, cryst. -free 3, 4 

112945-52-5 Silica, amorphous, fumed, cryst.-free 1, 3, 4 

60676-86-0 Silica, vitreous 1, 4, 8 

55465-40-2 Silicic acid, aluminum potassium sodium salt 4 

68037-74-1 

67762-90-7 

Siloxanes and silicones, di-Me, polymers with Me 

silsesquioxanes 

Siloxanes and Silicones, di-Me, reaction products with 

silica 

63148-52-7 Siloxanes and silicones, dimethyl, 4 

1 

4 

1, 4 


4 

4 

222




IUPAC 


Structure 

5324-84-5 Sodium 1-octanesulfonate 3 

2492-26-4 Sodium 2-mercaptobenzothiolate 2 

127-09-3 Sodium acetate 1, 3, 4 

532-32-1 Sodium benzoate 3 

144-55-8 Sodium bicarbonate 1, 2, 3, 4, 7 

7631-90-5 Sodium bisulfite 1, 3, 4 

1333-73-9 Sodium borate 1, 4, 6, 7 

7789-38-0 Sodium bromate 1, 2, 4 

7647-15-6 Sodium bromide 1, 2, 3, 4, 7 

1004542-84-0 Sodium bromosulfamate 8 

68610-44-6 Sodium caprylamphopropionate 4 

497-19-8 Sodium carbonate 1, 2, 3, 4, 8 

7775-09-9 Sodium chlorate 1, 4 

7647-14-5 Sodium chloride 

7758-19-2 Sodium chlorite 

3926-62-3 Sodium chloroacetate 3 

68608-68-4 Sodium cocaminopropionate 1 

142-87-0 Sodium decyl sulfate 1 

527-07-1 Sodium D-gluconate 4 

126-96-5 Sodium diacetate 1, 4 

2893-78-9 Sodium dichloroisocyanurate 2 

151-21-3 Sodium dodecyl sulfate 8 

1, 2, 3, 4, 

5, 8 

1, 2, 3, 4, 

5, 8 

6381-77-7 Sodium erythorbate (1:1) 1, 3, 4, 8 

126-92-1 Sodium ethasulfate 1 

141-53-7 Sodium formate 2, 8 

7681-38-1 Sodium hydrogen sulfate 4 

1310-73-2 Sodium hydroxide 

1, 2, 3, 4, 

7, 8 

7681-52-9 Sodium hypochlorite 1, 2, 3, 4, 8 

7681-82-5 Sodium iodide 4 

8061-51-6 Sodium ligninsulfonate 2 

18016-19-8 Sodium maleate (1:x) 8 

7681-57-4 Sodium metabisulfite 1 


223




IUPAC 


Structure 

7775-19-1 Sodium metaborate 3, 4 

16800-11-6 Sodium metaborate dihydrate 1, 4 

10555-76-7 Sodium metaborate tetrahydrate 1, 4, 8 

6834-92-0 Sodium metasilicate 1, 2, 4 

7631-99-4 Sodium nitrate 2 

7632-00-0 Sodium nitrite 1, 2, 4 

137-20-2 Sodium N-methyl-N-oleoyltaurate 4 

142-31-4 Sodium octyl sulfate 1 

1313-59-3 Sodium oxide 1 

11138-47-9 Sodium perborate 4 

10486-00-7 Sodium perborate tetrahydrate 1, 4, 5, 8 

7632-04-4 Sodium peroxoborate 1 

7775-27-1 Sodium persulfate 

1, 2, 3, 4, 

7, 8 

7632-05-5 Sodium phosphate 1, 4 

9084-06-4 Sodium polynaphthalenesulfonate 2 

7758-16-9 Sodium pyrophosphate 1, 2, 4 

54-21-7 Sodium salicylate 1, 4 

533-96-0 Sodium sesquicarbonate 1, 2 

1344-09-8 Sodium silicate 1, 2, 4 

9063-38-1 Sodium starch glycolate 2 

7757-82-6 Sodium sulfate 1, 2, 3, 4 

7757-83-7 Sodium sulfite 2, 4, 8 

540-72-7 Sodium thiocyanate 1, 4 

7772-98-7 Sodium thiosulfate 1, 2, 3, 4 

10102-17-7 Sodium thiosulfate, pentahydrate 1, 4 

650-51-1 Sodium trichloroacetate 1, 4 

1300-72-7 Sodium xylenesulfonate 1, 3, 4 

10377-98-7 Sodium zirconium lactate 1, 4 

64742-88-7 Solvent naphtha (petroleum), medium aliph. 1, 2, 4 

64742-96-7 Solvent naphtha, petroleum, heavy aliph. 2, 8 

64742-94-5 Solvent naphtha, petroleum, heavy arom. 1, 2, 4, 5, 8 

64742-95-6 Solvent naphtha, petroleum, light arom. 1, 2, 4 

8007-43-0 Sorbitan, (9Z)-9-octadecenoate (2:3) 4 


224




IUPAC 


Structure 

1338-43-8 Sorbitan, mono-(9Z)-9-octadecenoate 1, 2, 3, 4 

9005-65-6 

9005-67-8 

Sorbitan, mono-(9Z)-9-octadecenoate, poly(oxy-1,2 

ethanediyl) derivis. 

Sorbitan, monooctadecenoate, poly(oxy-1,2-ethanediyl) 

derivis. 

26266-58-0 Sorbitan, tri-(9Z)-9-octadecenoate 8 

 

 

3, 4 

3, 4 

10025-69-1 Stannous chloride dihydrate 1, 4 

9005-25-8 Starch 1, 2, 4 

68131-87-3 

Steam cracked distillate, cyclodiene dimer, 

dicyclopentadiene polymer 

8052-41-3 Stoddard solvent 1, 3, 4 

10476-85-4 Strontium chloride 4 

100-42-5 Styrene 2 

57-50-1 Sucrose 1, 2, 3, 4 

5329-14-6 Sulfamic acid 1, 4 

14808-79-8 Sulfate 1, 4 

68201-64-9 Sulfomethylated quebracho 2 

68608-21-9 Sulfonic acids, C10-16-alkane, sodium salts 6 

68439-57-6 

Sulfonic acids, C14-16-alkane hydroxy and C14-16 

alkene, sodium salts 

61789-85-3 Sulfonic acids, petroleum 1 

68608-26-4 Sulfonic acids, petroleum, sodium salts 3 

1 

1, 3, 4 

7446-09-5 Sulfur dioxide 2, 4, 8 

7664-93-9 Sulfuric acid 1, 2, 4, 7 

68955-19-1 Sulfuric acid, mono-C12-18-alkyl esters, sodium salts 4 

68187-17-7 Sulfuric acid, mono-C6-10-alkyl esters, ammonium salts 1, 4, 8 

14807-96-6 Talc 1, 3, 4, 6, 7 

8002-26-4 Tall oil 4, 8 

61791-36-4 Tall oil imidazoline 4 

68092-28-4 Tall oil, compound with diethanolamine 1 

65071-95-6 Tall oil, ethoxylated 4, 8 

8016-81-7 Tall-oil pitch 4 

61790-60-1 Tallow alkyl amines acetate 8 

72480-70-7 

Tar bases, quinoline derivatives, benzyl chloridequaternized 

1, 3, 4 

68647-72-3 Terpenes and Terpenoids, sweet orange-oil 1, 3, 4, 8 


225




IUPAC 


Structure 

8000-41-7 Terpineol 1, 3 

75-91-2 tert-Butyl hydroperoxide 1, 4 

614-45-9 tert-Butyl perbenzoate 1 

12068-35-8 Tetra-calcium-alumino-ferrite 1, 2, 4 

629-59-4 Tetradecane 8 

139-08-2 Tetradecyldimethylbenzylammonium chloride 1, 4, 8 

112-60-7 Tetraethylene glycol 1, 4 

112-57-2 Tetraethylenepentamine 1, 4 

55566-30-8 Tetrakis(hydroxymethyl)phosphonium sulfate 1, 2, 3, 4, 7 

681-84-5 Tetramethyl orthosilicate 1 

75-57-0 Tetramethylammonium chloride 

1, 2, 3, 4, 

7, 8 

1762-95-4 Thiocyanic acid, ammonium salt 2, 3, 4 

68-11-1 Thioglycolic acid 1, 2, 3, 4 

62-56-6 Thiourea 1, 2, 3, 4, 6 

68527-49-1 

Thiourea, polymer with formaldehyde and 1 

phenylethanone 

68917-35-1 Thuja plicata donn ex. D. don leaf oil 3 

7772-99-8 Tin(II) chloride 1 

 

1, 4, 8 

13463-67-7 Titanium dioxide 1, 2, 4 

36673-16-2 

Titanium(4+) 2-[bis(2-hydroxyethyl)amino]ethanolate 

propan-2-olate (1:2:2) 

74665-17-1 Titanium, iso-Pr alc. triethanolamine complexes 1, 4 

108-88-3 Toluene 1, 3, 4 

126-73-8 Tributyl phosphate 1, 2, 4 

81741-28-8 Tributyltetradecylphosphonium chloride 1, 3, 4 

7758-87-4 Tricalcium phosphate 1, 4 

12168-85-3 Tricalcium silicate 1, 2, 4 

87-90-1 Trichloroisocyanuric acid 2 

629-50-5 Tridecane 8 

102-71-6 Triethanolamine 1, 2, 4 

68299-02-5 Triethanolamine hydroxyacetate 3 

68131-71-5 Triethanolamine polyphosphate ester 1, 4, 8 

77-93-0 Triethyl citrate 1, 4 

78-40-0 Triethyl phosphate 1, 4 

 

1 


226




IUPAC 


Structure 

112-27-6 Triethylene glycol 1, 2, 3 

112-24-3 Triethylenetetramine 4 

122-20-3 Triisopropanolamine 1, 4 

14002-32-5 Trimethanolamine 3 

121-43-7 Trimethyl borate 8 

25551-13-7 Trimethylbenzene 1, 2, 4 

7758-29-4 Triphosphoric acid, pentasodium salt 1, 4 

1317-95-9 Tripoli 4 

6100-05-6 Tripotassium citrate monohydrate 4 

25498-49-1 Tripropylene glycol monomethyl ether 2 

68-04-2 Trisodium citrate 3 

6132-04-3 Trisodium citrate dihydrate 1, 4 

150-38-9 Trisodium ethylenediaminetetraacetate 1, 3 

19019-43-3 Trisodium ethylenediaminetriacetate 1, 4, 8 

7601-54-9 Trisodium phosphate 1, 2, 4 

10101-89-0 Trisodium phosphate dodecahydrate 1 

77-86-1 Tromethamine 3, 4 

73049-73-7 Tryptone 8 

1319-33-1 Ulexite 1, 2, 3, 8 

1120-21-4 Undecane 3, 8 

57-13-6 Urea 1, 2, 4, 8 

1318-00-9 Vermiculite 2 

24937-78-8 Vinyl acetate ethylene copolymer 1, 4 

25038-72-6 Vinylidene chloride/methylacrylate copolymer 4 

7732-18-5 Water 2, 4, 8 

8042-47-5 White mineral oil, petroleum 1, 2, 4 

1330-20-7 Xylenes 1, 2, 4 

8013-01-2 Yeast extract 8 

7440-66-6 Zinc 2 

3486-35-9 Zinc carbonate 2 

7646-85-7 Zinc chloride 1, 2 

1314-13-2 Zinc oxide 1, 4 

13746-89-9 Zirconium nitrate 2, 6 

62010-10-0 Zirconium oxide sulfate 1, 4 


227




IUPAC 


Structure 

7699-43-6 Zirconium oxychloride 1, 2, 4 

21959-01-3 Zirconium(IV) chloride tetrahydrofuran complex 5 

14644-61-2 Zirconium(IV) sulfate 2, 6 

197980-53-3 

Zirconium, 1,1'-((2-((2-hydroxyethyl)(2 

hydroxypropyl)amino)ethyl)imino)bis(2-propanol) 

complexes 

4 

68909-34-2 Zirconium, acetate lactate oxo ammonium complexes 4, 8 

174206-15-6 Zirconium, chloro hydroxy lactate oxo sodium complexes 4 

113184-20-6 Zirconium, hydroxylactate sodium complexes 1, 4 

101033-44-7 

Zirconium,tetrakis[2-[bis(2-hydroxyethyl)amino 

kN]ethanolato-kO] 

1, 2, 4, 5 

228



Table A-2 lists generic names of chemicals reported to be used in hydraulic fracturing fluids 

between 2005 and 2009. Generic chemical names provide limited information on the chemical, but 

are not specific enough to determine chemical structures. In some cases, the generic chemical name 

masks a specific chemical name and CASRN provided to the EPA and claimed as CBI by one or more 

of the nine hydraulic fracturing service companies. 

Table A-2. List of generic names of chemicals reportedly used in hydraulic fracturing fluids. In some cases, the 

generic chemical name masks a specific chemical name and CASRN provided to the EPA and claimed as CBI by 

one or more of the nine hydraulic fracturing service companies. 

Generic Chemical Name 

Reference 

2-Substituted aromatic amine salt 1, 4 

Acetylenic alcohol 1 

Acrylamide acrylate copolymer 4 

Acrylamide copolymer 1, 4 

Acrylamide modified polymer 4 

Acrylamide-sodium acrylate copolymer 4 

Acrylate copolymer 1 

Acrylic copolymer 1 

Acrylic polymer 1, 4 

Acrylic resin 4 

Acyclic hydrocarbon blend 1, 4 

Acylbenzylpyridinium choride 8 

Alcohol alkoxylate 1, 4 

Alcohol and fatty acid blend 2 

Alcohol ethoxylates 4 

Alcohols 1, 4 

Alcohols, C9-C22 1, 4 

Aldehydes 1, 4, 5 

Alfa-alumina 1, 4 

Aliphatic acids 1, 2, 3, 4 

Aliphatic alcohol 2 

Aliphatic alcohol glycol ether 3, 4 

Aliphatic alcohols, ethoxylated 2 

Aliphatic amine derivative 1 

Aliphatic carboxylic acid 4 

Alkaline bromide salts 1, 4 

Alkaline metal oxide 4 

Alkanes/alkenes 4 

Alkanolamine derivative 2 

Alkanolamine/aldehyde condensate 1, 2, 4 


229





Reference 

Alkenes 1, 4 

Alklaryl sulfonic acid 1, 4 

Alkoxylated alcohols 1 

Alkoxylated amines 1, 4 

Alkyaryl sulfonate 1, 2, 3, 4 

Alkyl alkoxylate 1, 4 

Alkyl amide 4 

Alkyl amine 1, 4 

Alkyl amine blend in a metal salt solution 1, 4 

Alkyl aryl amine sulfonate 4 

Alkyl aryl polyethoxy ethanol 3, 4 

Alkyl dimethyl benzyl ammonium chloride 4 

Alkyl esters 1, 4 

Alkyl ether phosphate 4 

Alkyl hexanol 1, 4 

Alkyl ortho phosphate ester 1, 4 

Alkyl phosphate ester 1, 4 

Alkyl phosphonate 4 

Alkyl pyridines 2 

Alkyl quaternary ammonium chlorides 1, 4 

Alkyl quaternary ammonium salt 4 

Alkylamine alkylaryl sulfonate 4 

Alkylamine salts 2 

Alkylaryl sulfonate 1, 4 

Alkylated quaternary chloride 1, 2, 4 

Alkylated sodium naphthalenesulphonate 2 

Alkylbenzenesulfonate 2 

Alkylbenzenesulfonic acid 1, 4, 5 

Alkylethoammonium sulfates 1 

Alkylphenol ethoxylates 1, 4 

Alkylpyridinium quaternary 4 

Alphatic alcohol polyglycol ether 2 

Aluminum oxide 1, 4 

Amide 4 

Amidoamine 1, 4 

Amine 1, 4 


230





Reference 

Amine compound 4 

Amine oxides 1, 4 

Amine phosphonate 1, 4 

Amine salt 1 

Amino compounds 1, 4 

Amino methylene phosphonic acid salt 1, 4 

Ammonium alcohol ether sulfate 1, 4 

Ammonium salt 1, 4 

Ammonium salt of ethoxylated alcohol sulfate 1, 4 

Amorphous silica 4 

Amphoteric surfactant 2 

Anionic acrylic polymer 2 

Anionic copolymer 1, 4 

Anionic polyacrylamide 1, 2, 4 

Anionic polyacrylamide copolymer 1, 4, 6 

Anionic polymer 1, 3, 4 

Anionic surfactants 2, 4, 6 

Antifoulant 1, 4 

Antimonate salt 1, 4 

Aqueous emulsion of diethylpolysiloxane 2 

Aromatic alcohol glycol ether 1 

Aromatic aldehyde 1, 4 

Aromatic hydrocarbons 3, 4 

Aromatic ketones 1, 2, 3, 4 

Aromatic polyglycol ether 1 

Arsenic compounds 4 

Ashes, residues 4 

Bentone clay 4 

Biocide 4 

Biocide component 1, 4 

Bis-quaternary methacrylamide monomer 4 

Blast furnace slag 4 

Borate salts 1, 2, 4 

Cadmium compounds 4 

Carbohydrates 1, 2, 4 

Carboxylmethyl hydroxypropyl guar 4 


231





Reference 

Cationic polyacrylamide 4 

Cationic polymer 2, 4 

Cedar fiber, processed 2 

Cellulase enzyme 1 

Cellulose derivative 1, 2, 4 

Cellulose ether 2 

Cellulosic polymer 2 

Ceramic 4 

Chlorous ion solution 1 

Chromates 1, 4 

Chrome-free lignosulfonate compound 2 

Citrus rutaceae extract 4 

Common white 4 

Complex alkylaryl polyo-ester 1 

Complex aluminum salt 1, 4 

Complex carbohydrate 2 

Complex organometallic salt 1 

Complex polyamine salt 7 

Complex substituted keto-amine 1 

Complex substituted keto-amine hydrochloride 1 

Copper compounds 6 

Coric oxide 4 

Cotton dust (raw) 2 

Cottonseed hulls 2 

Cured acrylic resin 1, 4 

Cured resin 1, 4, 5 

Cured urethane resin 1, 4 

Cyclic alkanes 1, 4 

Defoamer 4 

Dibasic ester 4 

Dicarboxylic acid 1, 4 

Diesel 1, 4, 6 

Dimethyl silicone 1, 4 

Dispersing agent 1 

Emulsifier 4 

Enzyme 4 


232





Reference 

Epoxy 4 

Epoxy resin 1, 4 

Essential oils 1, 4 

Ester Salt 2, 4 

Esters 2, 4 

Ether compound 4 

Ether salt 4 

Ethoxylated alcohol blend 4 

Ethoxylated alcohol/ester mixture 4 

Ethoxylated alcohols 1, 2, 4, 5, 7 

Ethoxylated alkyl amines 1, 4 

Ethoxylated amine blend 4 

Ethoxylated amines 1, 4 

Ethoxylated fatty acid 4 

Ethoxylated fatty acid ester 1, 4 

Ethoxylated nonionic surfactant 1, 4 

Ethoxylated nonylphenol 1, 2, 4 

Ethoxylated sorbitol esters 1, 4 

Ethylene oxide-nonylphenol polymer 4 

Fatty acid amine salt mixture 4 

Fatty acid ester 1, 2, 4 

Fatty acid tall oil 1, 4 

Fatty acids 1 

Fatty acid, ethoxylate 4 

Fatty alcohol alkoxylate 1, 4 

Fatty alkyl amine salt 1, 4 

Fatty amine carboxylates 1, 4 

Fatty imidazoline 4 

Fluoroaliphatic polymeric esters 1, 4 

Formaldehyde polymer 1 

Glass fiber 1, 4 

Glyceride esters 2 

Glycol 4 

Glycol blend 2 

Glycol ethers 1, 4, 7 

Ground cedar 2 


233





Reference 

Ground paper 2 

Guar derivative 1, 4 

Guar gum 4 

Haloalkyl heteropolycycle salt 1, 4 

Hexanes 1 

High molecular weight polymer 2 

High pH conventional enzymes 2 

Hydrocarbons 1 

Hydrogen solvent 4 

Hydrotreated and hydrocracked base oil 1, 4 

Hydrotreated distillate, light C9-16 4 

Hydrotreated heavy naphthalene 5 

Hydrotreated light distillate 2, 4 

Hydrotreated light petroleum distillate 4 

Hydroxyalkyl imino carboxylic sodium salt 2 

Hydroxycellulose 6 

Hydroxyethyl cellulose 1, 2, 4 

Imidazolium compound 4 

Inner salt of alkyl amines 1, 4 

Inorganic borate 1, 4 

Inorganic chemical 4 

Inorganic particulate 1, 4 

Inorganic salt 2, 4 

Iso-alkanes/n-alkanes 1, 4 

Isomeric aromatic ammonium salt 1, 4 

Latex 2, 4 

Lead compounds 4 

Low toxicity base oils 1, 4 

Lubra-Beads course 4 

Maghemite 1, 4 

Magnetite 1, 4 

Metal salt 1 

Metal salt solution 1 

Mineral 1, 4 

Mineral fiber 2 

Mineral filler 1 


234





Reference 

Mineral oil 4 

Mixed titanium ortho ester complexes 1, 4 

Modified acrylamide copolymer 2, 4 

Modified acrylate polymer 4 

Modified alkane 1, 4 

Modified bentonite 4 

Modified cycloaliphatic amine adduct 1, 4 

Modified lignosulfonate 2, 4 

Naphthalene derivatives 1, 4 

Neutralized alkylated napthalene sulfonate 4 

Nickel chelate catalyst 4 

Nonionic surfactant 1 

N-tallowalkyltrimethylenediamines 4 

Nuisance particulates 1, 2, 4 

Nylon 4 

Olefinic sulfonate 1, 4 

Olefins 1, 4 

Organic acid salt 1, 4 

Organic acids 1, 4 

Organic alkyl amines 4 

Organic chloride 4 

Organic modified bentonite clay 4 

Organic phosphonate 1, 4 

Organic phosphonate salts 1, 4 

Organic phosphonic acid salts 1, 4 

Organic polymer 4 

Organic polyol 4 

Organic salt 1, 4 

Organic sulfur compound 1, 4 

Organic surfactants 1 

Organic titanate 1, 4 

Organo amino silane 4 

Organo phosphonic acid 4 

Organo phosphonic acid salt 4 

Organometallic ammonium complex 1 

Organophilic clay 4 


235





Reference 

Oxidized tall oil 2 

Oxoaliphatic acid 2 

Oxyalkylated alcohol 1, 4 

Oxyalkylated alkyl alcohol 2, 4 

Oxyalkylated alkylphenol 1, 2, 3, 4 

Oxyalkylated fatty acid 1, 4 

Oxyalkylated fatty alcohol salt 2 

Oxyalkylated phenol 1, 4 

Oxyalkylated phenolic resin 4 

Oxyalkylated polyamine 1 

Oxyalkylated tallow diamine 2 

Oxyethylated alcohol 2 

Oxylated alcohol 1, 4 

P/F resin 4 

Paraffinic naphthenic solvent 1 

Paraffinic solvent 1, 4 

Paraffin inhibitor 4 

Paraffins 1 

Pecan shell 2 

Petroleum distallate blend 2, 3, 4 

Petroleum gas oils 1 

Petroleum hydrocarbons 4 

Petroleum solvent 2 

Phosphate ester 1, 4 

Phosphonate 2 

Phosphonic acid 1, 4 

Phosphoric acid, mixed polyoxyalkylene aryl and alkyl esters 4 

Plasticizer 1, 2 

Polyacrylamide copolymer 4 

Polyacrylamides 1 

Polyacrylate 1, 4 

Polyactide resin 4 

Polyalkylene esters 4 

Polyaminated fatty acid 2 

Polyaminated fatty acid surfactants 2 

Polyamine 1, 4 


236





Reference 

Polyamine polymer 4 

Polyanionic cellulose 1 

Polyaromatic hydrocarbons 6 

Polycyclic organic matter 6 

Polyelectrolyte 4 

Polyether polyol 2 

Polyethoxylated alkanol 2, 3, 4 

Polyethylene copolymer 4 

Polyethylene glycols 4 

Polyethylene wax 4 

Polyglycerols 2 

Polyglycol 2 

Polyglycol ether 6 

Polylactide resin 4 

Polymer 2, 4 

Polymeric hydrocarbons 3, 4 

Polymerized alcohol 4 

Polymethacrylate polymer 4 

Polyol phosphate ester 2 

Polyoxyalkylene phosphate 2 

Polyoxyalkylene sulfate 2 

Polyoxyalkylenes 1, 4, 7 

Polyphenylene ether 4 

Polyphosphate 4 

Polypropylene glycols 2 

Polyquaternary amine 4 

Polysaccaride polymers in suspension 2 

Polysaccharide 4 

Polysaccharide blend 4 

Polyvinylalcohol/polyvinylactetate copolymer 4 

Potassium chloride substitute 4 

Quarternized heterocyclic amines 4 

Quaternary amine 2, 4 

Quaternary amine salt 4 

Quaternary ammonium chloride 4 

Quaternary ammonium compound 1, 2, 4 


237





Reference 

Quaternary ammonium salts 1, 2, 4 

Quaternary compound 1, 4 

Quaternary salt 1, 4 

Quaternized alkyl nitrogenated compd 4 

Red dye 4 

Refined mineral oil 2 

Resin 4 

Salt of amine-carbonyl condensate 3, 4 

Salt of fatty acid/polyamine reaction product 3, 4 

Salt of phosphate ester 1 

Salt of phosphono-methylated diamine 1, 4 

Salts 4 

Salts of oxyalkylated fatty amines 4 

Sand 4 

Sand, AZ silica 4 

Sand, brown 4 

Sand, sacked 4 

Sand, white 4 

Secondary alcohol 1, 4 

Silica sand, 100 mesh, sacked 4 

Silicone emulsion 1 

Silicone ester 4 

Sodium acid pyrophosphate 4 

Sodium calcium magnesium polyphosphate 4 

Sodium phosphate 4 

Sodium salt of aliphatic amine acid 2 

Sodium xylene sulfonate 4 

Softwood dust 2 

Starch blends 6 

Substituted alcohol 1, 2, 4 

Substituted alkene 1 

Substituted alklyamine 1, 4 

Substituted alkyne 4 

Sulfate 4 

Sulfomethylated tannin 2, 5 

Sulfonate 4 


238





Reference 

Sulfonate acids 1 

Sulfonate surfactants 1 

Sulfonated asphalt 2 

Sulfonic acid salts 1, 4 

Sulfur compound 1, 4 

Sulphonic amphoterics 4 

Sulphonic amphoterics blend 4 

Surfactant blend 3, 4 

Surfactants 1, 2, 4 

Synthetic copolymer 2 

Synthetic polymer 4 

Tallow soap 4 

Telomer 4 

Terpenes 1, 4 

Titanium complex 4 

Triethanolamine zirconium chelate 1 4 

Triterpanes 4 

Vanadium compounds 4 

Wall material 1 

Walnut hulls 1, 2, 4 

Zirconium complex 2, 4 

Zirconium salt 4 

239



Table A-3 contains a list of chemicals with CASRNs that have been detected in flowback and 

produced water (collectively referred to as “hydraulic fracturing wastewater”). The table identifies 

chemicals that are also reported to be used in hydraulic fracturing fluids (Table A-1). 

Table A-3. List of CASRNs and names of chemicals detected in hydraulic fracturing wastewater. Chemicals also 

reportedly used in hydraulic fracturing fluids are marked with an “.” 

CASRN Chemical Name 

Also Listed in 

Table A - 1 

Reference 

87-61-6 1,2,3-Trichlorobenzene 3, 9 

120-82-1 1,2,4-Trichlorobenzene 9 

95-63-6 1,2,4-Trimethylbenzene 3, 9, 10 

57-55-6 1,2-Propanediol 3, 9 

108-67-8 1,3,5-Trimethylbenzene 3, 9, 10 

123-91-1 1,4-Dioxane 9, 10 

105-67-9 2,4-Dimethylphenol 3, 9, 10 

87-65-0 2,6-Dichlorophenol 3, 9 

91-57-6 2-Methylnaphthalene 3, 9, 10 

95-48-7 2-Methylphenol 3, 9, 10 

79-31-2 2-Methylpropanoic acid 10 

109-06-8 2-Methylpyridine 3, 9 

503-74-2 3-Methylbutanoic acid 10 

108-39-4 3-Methylphenol 3, 9, 10 

106-44-5 4-Methylphenol 3, 9, 10 

57-97-6 7,12-Dimethylbenz(a)anthracene 3, 9 

64-19-7 Acetic acid 3, 9, 10 

67-64-1 Acetone 3, 9, 10 

98-86-2 Acetophenone 3, 9 

107-02-8 Acrolein 9 

107-13-1 Acrylonitrile 3, 9 

309-00-2 Aldrin 3, 9 

7429-90-5 Aluminum 3, 9, 10 

7664-41-7 Ammonia 3, 9, 10 

7440-36-0 Antimony 3, 9, 10 

12672-29-6 Aroclor 1248 3, 9 

7440-38-2 Arsenic 3, 9, 10 

7440-39-3 Barium 3, 9, 10 

71-43-2 Benzene 3, 9, 10 

50-32-8 Benzo(a)pyrene 3, 9 

205-99-2 Benzo(b)fluoranthene 3, 9 

191-24-2 Benzo(g,h,i)perylene 3, 9, 10 

207-08-9 Benzo(k)fluoranthene 3, 9 

100-51-6 Benzyl alcohol 3, 9, 10 


240




CASRN 

7440-41-7 

Chemical Name 

Beryllium 


Table A -1 

319-85-7 beta-1,2,3,4,5,6-Hexachlorocyclohexane 3, 9 

111-44-4 Bis(2-chloroethyl) ether 3, 9 

Reference 

3, 9, 10 

7440-42-8 Boron 3, 9, 10 

24959-67-9 Bromide (-1) 3, 9, 10 

75-27-4 Bromodichloromethane 3 

75-25-2 

107-92-6 

Bromoform 

Butanoic acid 

3, 9, 10 

9, 10 

104-51-8 

Butylbenzene 9, 10 

7440-43-9 Cadmium 3, 9, 10 

10045-97-3 Caesium 137 3 

7440-70-2 Calcium 3, 9, 10 

124-38-9 Carbon dioxide 3, 9, 10 

75-15-0 Carbon disulfide 3, 9 

16887-00-6 Chloride 

3, 9, 10 

7782-50-5 Chlorine 3, 10 

124-48-1 Chlorodibromomethane 3 

67-66-3 Chloroform 3, 9, 10 

74-87-3 Chloromethane 3, 10 

7440-47-3 Chromium 3, 9, 10 

16065-83-1 Chromium (III), insoluble salts 3 

18540-29-9 Chromium (VI) 3, 10 

7440-48-4 Cobalt 3, 9, 10 

7440-50-8 Copper 

98-82-8 Cumene 3, 9 

3, 9, 10 

57-12-5 Cyanide, free 3, 9, 10 

319-86-8 delta-Hexachlorocyclohexane 9 

117-81-7 Di(2-ethylhexyl) phthalate 

53-70-3 Dibenz(a,h)anthracene 3, 9 

3, 9, 10 

84-74-2 Dibutyl phthalate 3, 9, 10 

75-09-2 Dichloromethane 9, 10 

60-57-1 Dieldrin 9 

84-66-2 Diethyl phthalate 9 

117-84-0 

122-39-4 

Dioctyl phthalate 

Diphenylamine 

959-98-8 Endosulfan I 3, 9 

33213-65-9 Endosulfan II 3, 9 

7421-93-4 Endrin aldehyde 3, 9 

9, 10 

3, 9 


241




CASRN 

100-41-4 

107-21-1 

Chemical Name 

Ethylbenzene 


Table A -1 

Ethylene glycol 3, 9 

 

Reference 

3, 9, 10 

206-44-0 

Fluoranthene 3, 9 

86-73-7 Fluorene 3, 9, 10 

16984-48-8 Fluoride 3, 9, 10 

64-18-6 Formic acid 10 

76-44-8 Heptachlor 3, 9 

1024-57-3 Heptachlor epoxide 3, 9 

111-14-8 

Heptanoic acid 

142-62-1 

Hexanoic acid 10 

193-39-5 Indeno(1,2,3-cd)pyrene 3, 9 

7439-89-6 Iron 

67-63-0 

Isopropanol 3, 9 

7439-92-1 Lead 

58-89-9 Lindane 3, 9 

10 

3, 9, 10 

3, 9, 10 

7439-93-2 Lithium 3, 9, 10 

7439-95-4 Magnesium 3, 9, 10 

7439-96-5 Manganese 3, 9, 10 

7439-97-6 

67-56-1 

Mercury 

Methanol 3, 9 

74-83-9 Methyl bromide 3, 9 

3, 9, 10 

78-93-3 Methyl ethyl ketone 3, 9, 10 

7439-98-7 Molybdenum 3, 9, 10 

91-20-3 Naphthalene 

7440-02-0 

Nickel 

86-30-6 N-Nitrosodiphenylamine 3, 9 

72-55-9 p,p'-DDE 3, 9 

3, 9, 10 

3, 9, 10 

99-87-6 p-Cymene 9, 10 

109-52-4 

Pentanoic acid 

85-01-8 Phenanthrene 

108-95-2 

298-02-2 

Phorate 9 

10 

3, 9, 10 

Phenol 3, 9, 10 

7723-14-0 Phosphorus 3, 9 

7440-09-7 Potassium 3, 9, 10 

79-09-4 Propionic acid 10 

103-65-1 

Propylbenzene 

129-00-0 

Pyrene 9, 10 

110-86-1 Pyridine 3, 9, 10 

9 


242




CASRN 

13982-63-3 

Chemical Name 

Radium 226 


Table A -1 

7440-14-4 Radium 226,228 3 

Reference 

3, 10 

15262-20-1 Radium 228 3, 10 

94-59-7 Safrole 3, 9 

135-98-8 sec-Butylbenzene 9 

7782-49-2 Selenium 3, 9, 10 

7631-86-9 Silica 10 

7440-21-3 Silicon (elemental) 10 

7440-22-4 Silver 3, 9, 10 

7440-23-5 Sodium 3, 9, 10 

7440-24-6 Strontium 3, 9, 10 

14808-79-8 Sulfate 

14265-45-3 Sulfite 3 

127-18-4 Tetrachloroethylene 3, 9 

3, 9, 10 

7440-28-0 Thallium and Compounds 3, 9, 10 

7440-31-5 Tin 9, 10 

7440-32-6 Titanium 3, 9, 10 

108-88-3 Toluene 

3, 9, 10 

7440-62-2 Vanadium 3, 10 

1330-20-7 Xylenes 

7440-66-6 Zinc 

7440-67-7 Zirconium 3 

3, 9, 10 

3, 9, 10 

243



Table A-4 contains a list of chemicals and properties that are detected in flowback and produced 

water (collectively referred to as “hydraulic fracturing wastewater”). 

Table A-4. List of chemicals and properties detected in hydraulic fracturing wastewater. 

Chemical Name / Property Reference 

Alkalinity 3, 9, 10 

Alkalinity, carbonate (as CaCO 3 ) 3, 9, 10 

Alpha radiation 3 

Aluminum, dissolved 3, 9 

Barium strontium P.S. 3 

Barium, dissolved 3, 9 

Beta radiation 3 

Bicarbonates (HCO 3 ) 3, 10 

Biochemical oxygen demand 3, 9, 10 

Cadmium, dissolved 3, 9 

Calcium, dissolved 3, 9 

Chemical oxygen demand 3, 9, 10 

Chromium (VI), dissolved 3 

Chromium, dissolved 3, 9 

Cobalt, dissolved 3, 9 

Coliform 3 

Color 3 

Conductivity 3, 9, 10 

Hardness as CaCO 3 3, 9, 10 

Heterotrophic plate count 3 

Hexanoic acid 10 

Iron, dissolved 3, 9 

Lithium, dissolved 3, 9 

Magnesium, dissolved 3, 9 

Chemical Name / Property Reference 

Manganese, dissolved 3, 9 

Nickel, dissolved 3, 9 

Nitrate, as N 3, 9, 10 

Nitrogen, total as N 3 

Oil and grease 3, 9, 10 

Petroleum hydrocarbons 3 

pH 3, 9, 10 

Phenols 3 

Potassium, dissolved 3, 9 

Salt 3 

Scale inhibitor 3 

Selenium, dissolved 3, 9 

Silver, dissolved 3, 10 

Sodium, dissolved 3, 10 

Strontium, dissolved 3, 10 

Surfactants 3 

Total alkalinity 3, 9, 10 

Total dissolved solids 3, 9, 10 

Total Kjeldahl nitrogen 3, 9, 10 

Total organic carbon 3, 9, 10 

Total sulfide 9 

Total suspended solids 3, 9, 10 

Volatile acids 3, 9 

Zinc, dissolved 3, 9 

244



References 

1. US House of Representatives 2011. Chemicals Used in Hydraulic Fracturing. Available at 

http://democrats.energycommerce.house.gov/sites/default/files/documents/Hydraulic%2 

0Fracturing%20Report%204.18.11.pdf. Accessed November 27, 2012. 

2. Colborn, T., Kwiatkowski, C., Schultz, K. and Bachran, M. 2011. Natural Gas Operations from 

a Public Health Perspective. Human and Ecological Risk Assessment 17 (5): 1039-1056. 

3. New York State Department of Environmental Conservation. 2011. Supplemental Generic 


(Revised Draft). Well Permit Issuance for Horizontal Drilling and High-Volume Hydraulic 


Available at http://www.dec.ny.gov/energy/75370.html. Accessed September 1, 2011. 

4. US Environmental Protection Agency. 2011. Data received from oil and gas exploration and 

production companies, including hydraulic fracturing service companies. Non-confidential 

business information source documents are located in Federal Docket ID: EPA-HQ-ORD 

2010-0674. Available at http://www.regulations.gov. Accessed November 14, 2012. 

5. Material Safety Data Sheets. (a) Encana/Halliburton Energy Services, Inc.: Duncan, 

Oklahoma. Provided by Halliburton Energy Services during an onsite visit by the EPA on 

May 10, 2010; (b) Encana Oil and Gas (USA), Inc.: Denver, Colorado. Provided to US EPA 

Region 8. 

6. US Environmental Protection Agency, Office of Water. 2004. Evaluation of Impacts to 

Underground Sources of Drinking Water by Hydraulic Fracturing of Coalbed Methane 

Reservoirs. EPA 816-R-04-003. Available at http://water.epa.gov/type/groundwater/uic/ 

class2/hydraulicfracturing/wells_coalbedmethanestudy.cfm. Accessed November 27, 2012. 

7. Pennsylvania Department of Environmental Protection. 2010. Chemicals Used by Hydraulic 

Fracturing Companies in Pennsylvania for Surface and Hydraulic Fracturing Activities. 

Available at http://files.dep.state.pa.us/OilGas/BOGM/BOGMPortalFiles/MarcellusShale/ 

Frac%20list%206-30-2010.pdf. Accessed November 27, 2012. 

8. Ground Water Protection Council. 2012. FracFocus well records: January 1, 2011, through 

February 27, 2012. Available at http://www.fracfocus.org/. 

9. Hayes, T. 2009. Sampling and Analysis of Water Streams Associated with the Development 

of Marcellus Shale Gas. Gas Technology Institute for Marcellus Shale Coalition. Available at 

http://eidmarcellus.org/wp-content/uploads/2012/11/MSCommission-Report.pdf. 


10. US Environmental Protection Agency. 2011. Sampling Data for Flowback and Produced 

Water Provided to EPA by Nine Oil and Gas Well Operators (Non-Confidential Business 

Information). Available at http://www.regulations.gov/#!docketDetail;rpp=100;so=DESC; 

sb=docId;po=0;D=EPA-HQ-ORD-2010-0674. Accessed November 27, 2012. 

245



Appendix B: Stakeholder Engagement 90 

B.1. Stakeholder Engagement Road Map for the EPA’s Study on the Potential 

Impacts of Hydraulic Fracturing on Drinking Water Resources 

On March 18, 2010, at the request of the U.S. Congress, the EPA announced plans to develop a 

comprehensive research study on the potential impact of hydraulic fracturing on drinking water 

resources. The EPA believes a transparent, research-driven approach with significant stakeholder 

involvement can address questions about hydraulic fracturing and strengthen our clean energy 

future. The road map below outlines the EPA’s plans to build upon its commitment to transparency 

and stakeholder engagement coordinated during the development of the Study Plan and will help 

inform the report of results. 

Goals of Strengthened Stakeholder Engagement 

• Increase technical engagement with the stakeholder community to ensure that the EPA 

has ongoing access to a broad range of expertise and data outside the agency. 

• Improve public understanding of the goals and design of the study. 

• Ensure that the EPA is current on changes in industry practices and technologies so the 

report of results reflects an up-to-date picture of hydraulic fracturing operations. 

• Obtain timely and constructive feedback on projects undertaken as part of the study. 

Increased Technical Engagement 

In November 2012, the EPA held five roundtables focused on each stage of the water cycle: 

• Water acquisition. This study takes steps to examine potential changes in the quantity of 

water available for drinking and potential changes in drinking water quality that result 

from acquisition for hydraulic fracturing. The EPA is aware that the use of recycling is 

rapidly growing and that this may affect the need to acquire water for hydraulic fracturing. 

• Chemical mixing. The study examines the potential release of chemicals used in hydraulic 

fracturing to surface and ground water through onsite spills and/or leaks and compiles 

information on hydraulic fracturing fluids and chemicals from publicly available data, data 

provided by nine hydraulic fracturing service companies and other sources. 

• Flowback. The study examines available data regarding release to surface or ground water 

through spills or leakage from onsite storage. 

• Water treatment and disposal. The study examines the potential for contaminants to reach 

drinking water due to surface water discharge, the effectiveness of current wastewater 

treatment, and the potential formation of disinfection byproducts in drinking water 

treatment facilities. 

90 The text and figure included in this appendix were taken from http://www.epa.gov/hfstudy/stakeholderroadmap.html. 

Please see this website for updated information as it becomes available. 

246



• Well injection. The study takes steps to examine the potential for release of hydraulic 

fracturing fluids to ground water due to inadequate well construction or operation, 

movement of hydraulic fracturing fluids from the target formation to drinking water 

aquifers through local man-made or natural features (e.g., other production or abandoned 

wells and existing faults or fractures). 

Based on feedback from these roundtables, the EPA will host in-depth technical workshops to 

address specific issues in greater detail. These technical workshops will begin in February 2013 

and continue as needed. Upon completion of the last technical workshop, the EPA will reconvene 

the original roundtables to review the work addressed in the technical workshop series. 

Improve Public Understanding 

To improve public understanding of the study, the EPA staff will increase the frequency of 

webinars. For instance, after the initial set of roundtables and each technical workshop, the EPA 

will host a webinar to report out to the public on these. The EPA will continue to provide regular 

electronic updates to its list of stakeholders. 

In addition to the webinars, the EPA staff will regularly update its hydraulic fracturing study 

website with up-to-date materials and identify opportunities for briefings and updates on the study 

to stakeholders (e.g., annual or regional meetings of industry trade associations, annual meetings of 

environmental/public health groups, academic conferences, annual or regional meetings of water 

utilities, and tribal meetings). 

The EPA has previously committed to the release in December 2012 of a progress report on the 

study. While the progress report will not make any final findings or conclusions, it will provide the 

public with an update on study activities and future work. 

Ensure the EPA is Current on Industry Practices 

To ensure that the EPA is up-to-date on evolving industry practices and technologies, the EPA will 

publish a Federal Register notice in late 2012 to create a docket where stakeholders can submit 

peer-reviewed data from ongoing or completed studies. This initial request will be followed up with 

requests in 2013 and 2014. 

Obtain Timely Feedback 

The EPA intends to receive timely feedback on the projects conducted as part of the study through 

the roundtables and technical workshops described above. In addition, the EPA's Science Advisory 

Board is forming a panel of independent experts who will provide advice and review under the 

auspices of the Science Advisory Board on the EPA's hydraulic fracturing research described in its 

2012 Progress Report. The EPA plans to use such advice for the development of a report of results, 

estimated to be released in late 2014, which will also be reviewed by the Science Advisory Board. In 

addition, this panel may also provide advice on other technical documents and issues related to 

hydraulic fracturing upon further request by the EPA. The panel will provide opportunities for 

public comment in connection with these activities. 

247



B.2 Stakeholder Road Map and Timeline 

Increase technical engagement with the stakeholder community to ensure that the EPA has 

ongoing access to a broad range of expertise and data outside the agency. 

Plan: The week of November 12, 2012, EPA held five roundtables focused on each stage of the water 

cycle, to be followed in Spring 2013 by a series of technical workshops on topics identified during 

the roundtables. 

Implementation: 

• Identify participants for meetings (September 2012): 

o 

o 

The EPA consulted with industry, non-governmental organizations, states, and 

tribes through a series of one-on-one meetings in September to present the plan 

for the roundtables and ask for potential invitees with technical expertise. The EPA 

then selected invitees with appropriate technical backgrounds. 

Roundtable participants numbered 15-20 in addition to the EPA staff. 

• Kick-off (October 2012) 

o 

The EPA hosted a kick-off (virtual) meeting with technical representatives 

representing a broad range of stakeholders to lay out the context, goals, and 

logistics for the roundtables. 

• Roundtables (November 14–16, 2012) 

o 

o 

Each meeting was professionally facilitated. 

All roundtables occurred in DC. These were half-day meetings. 

• Workshops (February 2013 through April 2013) 

• Second round of roundtables (Summer/Fall 2013) 

Obtain timely and constructive feedback on projects undertaken as part of the study and 

ensure that the EPA is current on changes in industry practices and technologies so the 

report of results reflects an up-to-date picture of hydraulic fracturing operations. 

Plan: Issue Federal Register notices in 2012, 2013, and 2014 requesting additional data and 

information to inform the study. 91 The notices will request peer-reviewed data and reports that can 

help answer the research questions, for example, the content of hydraulic fracturing flowback and 

produced water; the location of prior wastewater treatment pits, ponds, lagoons, and tanks; specific 

sources of water used for hydraulic fracturing; specific water quality requirements for use of water 

or reuse of waste water in hydraulic fracturing; partitioning of constituents into gas solid and liquid 

components (particularly the fate of metals, organics, and radionuclides). 

91 The first Federal Register notice was published in November 2012 and is available at http://www.gpo.gov/fdsys/ 

pkg/FR-2012-11-09/pdf/2012-27452.pdf. 

248



Implementation: 

• Technical workshops on specific technical topics suggested by roundtable participants 

(begin February 2013) 

• These sessions will flow from roundtable discussions. The EPA will convene experts to 

address specific issues of data collection, method or data interpretation (i.e., how to find 

more comprehensive/reliable spill data; how to get good data for the environmental 

justice analysis, etc.). The EPA will issue the first Federal Register notice in late 2012 to 

request peer-reviewed data and studies that can help answer the research questions. 

Additional Federal Register notices will request peer-reviewed information and will be 

published annually in 2013 and 2014. 

Improve public understanding of the goals and design of the study. 

Plan: In addition to the organized technical meetings, the EPA will seek opportunities (such as 

association or state organization meetings) to provide informal briefings and updates on the study 

to a diverse range of stakeholders, including states, non-governmental organizations, academia, and 

industry. The EPA will also increase the frequency of webinars, hosting them after each technical 

meeting to report out to the public on the discussion. 

Implementation: The EPA will host monthly webinars following the initial set of roundtables and 

each technical workshop to inform the public of topics discussed. The EPA will develop and publish 

a calendar of events where presentations on the study will be made. 

249



Figure B-1. Timeline for technical roundtables and workshops. The goals of this enhanced engagement process are to improve public understanding of the study, 

ensure that the EPA is current on changes in industry practices and technologies so that the report of results reflects an up-to-date picture of hydraulic fracturing 

operations, and obtain timely and constructive feedback on ongoing research projects. 

250



Appendix C: Summary of QAPPs 

This appendix provides a quick reference table for QAPPs associated with the research projects that 

comprise the EPA’s Study of the Potential Impacts of Drinking Water Resources. Current versions of 

the QAPPs are available at http://www.epa.gov/hfstudy/qapps.html. 

Table C-1. QAPPs associated with the research projects discussed in this progress report. 







Subsurface Migration 

Modeling 



Source Apportionment 

Studies 

Wastewater Treatability 

Studies 


Analytical Method 

Development 

QAPP Title 

QAPP for Hydraulic Fracturing Data and Literature Evaluation for the 

EPA’s Study of the Potential Impacts of Hydraulic Fracturing on 


QAPP for Hydraulic Fracturing Surface Spills Data Analysis 

Final QAPP for the Evaluation of Information on Hydraulic Fracturing 

QAPP for Analysis of Data Received from Nine Hydraulic Fracturing 

Service Companies 

QAPP for Hydraulic Fracturing 

National Hydraulic Fracturing Study Evaluation of Existing Production 

Well File Contents: QAPP 

Supplemental Programmatic QAPP for Work Assignment 4-58: 


Well File Contents 

Supplemental Programmatic QAPP for Work Assignment 4-58: 


Well File Contents 

QAPP for Analysis of Data Extracted from FracFocus 

Analysis of Environmental Hazards Related to Hydrofracturing 

QAPP for Surface Water Transport of Hydraulic Fracturing-Derived 

Waste Water 

Data Collection/Mining for Hydraulic Fracturing Case Studies 

Modeling the Impact of Hydraulic Fracturing on Water Resources 

Based on Water Acquisition Scenarios 

QAPP for Hydraulic Fracturing Waste Water Source Apportionment 

Study 

Fate, Transport, and Characterization of Contaminants in Hydraulic 

Fracturing Water in Wastewater Treatment Processes 

Formation of Disinfection By-Products from Hydraulic Fracturing Fluid 

Constituents: QAPP 

QAPP for the Chemical Characterization of Select Constituents 

Relevant to Hydraulic Fracturing 

QAPP for the Interlaboratory Verification and Validation of Diethylene 

Glycol, Triethylene Glycol, Tetraethylene Glycol, 2-Butoxyethanol and 

2-Methoxyethanol in Ground and Surface Waters by Liquid 

Chromatography/Tandem Mass Spectrometry 


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QAPP Title 

QAPP: Health and Toxicity Theme, Hydraulic Fracturing Study 


QAPP for Chemical Information Quality Review and Physicochemical 

Property Calculations for Hydraulic Fracturing Chemical Lists 

Las Animas and Huerfano 

Hydraulic Fracturing Retrospective Case Study, Raton Basin, CO 

Counties, Colorado 

Hydraulic Fracturing Retrospective Case Study, Bakken Shale, 

Dunn County, North Dakota 

Killdeer and Dunn County, ND 

Bradford County, 

Pennsylvania 

Washington County, 

Pennsylvania 

Wise County, Texas 

Hydraulic Fracturing Retrospective Case Study, Bradford- 

Susquehanna Counties, PA 

Hydraulic Fracturing Retrospective Case Study, Marcellus Shale, 

Washington County, PA 

Hydraulic Fracturing Retrospective Case Study, Wise and Denton 

Cos., TX 

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Appendix D: Divisions of Geologic Time 

Figure E-1 is reproduced from a USGS fact 

sheet, “ Divisions of 

Geologic Time: 

Major 

Chronostratigraphic and Geochronological 

Units.” A geologic timescale relates rock 

layers to time. 

Chronstratigraphic units refer to specific 

rock layers while geochronological units 

refer to specific time periods. 

Reference 

US Geological Survey. 2010. Divisions of 

Geologic Time: Major Chronostratigraphic 

and Geochronological Units. Fact Sheet 

2010-3059. US Geological Survey. Available 

at http://pubs.usgs.gov/fs/ 

2010/3059/pdf/FS10-3059.pdf. Accessed 


Figure D-1. Divisions of geologic time approved by 

the USGS Geologic Names Committee (2010).The 

chart shows major chronostratigraphic and 

geochronologic units. 

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Glossary 

Acid mine drainage: Drainage of water from areas that have been mined for coal of other mineral 

ores. The water has a low pH because of its contact with sulfur-bearing material and is harmful to 

aquatic organisms. (2) 

Adsorption: Adhesion of molecules of gas, liquid, or dissolved solids to a surface. (2) 

Aeration: A process that promotes biological degradation of organic matter in water. The process 

may be passive (as when waste is exposed to air) or active (as when a mixing or bubbling device 

introduces the air). (2) 

Ambient water quality: Natural concentration of water quality constituents prior to mixing of 

either point or nonpoint source load of contaminants. Reference ambient concentration is used to 

indicate the concentration of a chemical that will not cause adverse impact to human health. (2) 

Analysis of existing data: The process of gathering and summarizing existing data from various 

sources to provide current information on hydraulic fracturing activities. 

Analyte: The element, ion, or compound that an analysis seeks to identify; the compound of 

interest. (2) 

Annulus: Either the space between the casing of a well and the wellbore or the space between the 

tubing and casing of a well. (2) 

API number: A unique identifying number for all oil and gas wells drilled in the United States. The 

system was developed by the American Petroleum Institute. (1) 

Aquifer: An underground geological formation, or group of formations, containing water. A source 

of ground water for wells and springs. (2) 

Baseline data: Initial information on a program or program components collected prior to receipt 

of services or participation activities. Often gathered through intake interviews and observations 

and used later for comparing measures that determine changes in a program. (2) 

Case study: An approach often used in research to better understand real-world situations or 

events using a systematic process for the collection and analysis of data. 

Prospective case study: A study of sites where hydraulic fracturing will occur after the 

research is initiated. These case studies allow sampling and characterization of the site 

prior to, and after, water extraction, drilling, hydraulic fracturing fluid injection, flowback, 

and gas production. The data collected during prospective case studies will allow the EPA to 

evaluate any changes in water quality over time. 

Retrospective case study: A study of sites where hydraulic fracturing has occurred nearby, 

with a focus on sites with reported instances of drinking water resource contamination. 

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These studies will use existing data, sampling, and possibly modeling to determine whether 

reported impacts are due to hydraulic fracturing activities or other sources. 

Casing: Pipe cemented in the well to seal off formation fluids and to keep the hole from caving in. 

(1) 

Chemical Abstracts Service: Provides information on chemical properties and interactions. Every 

year, the Chemical Abstracts Service updates and writes new chemical abstracts on well over a 

million different chemicals, including each chemical’s composition, structure, characteristics, and 

different names. Each abstract is accompanied by a registration number, or CASRN. (2) 

Coalbed methane: Methane contained in coal seams. A coal seam is a layer or stratum of coal 

parallel to the rock stratification. 

Confidential business information (CBI): Information that contains trade secrets, commercial or 

financial information, or other information that has been claimed as confidential by the submitter. 

The EPA has special procedures for handling such information. (2) 

Contaminant: A substance that is either present in an environment where it does not belong or is 

present at levels that might cause harmful (adverse) health effects. (2) 

Conventional reservoir: A reservoir in which buoyant forces keep hydrocarbons in place below a 

sealing caprock. Reservoir and fluid characteristics of conventional reservoirs typically permit oil 

or natural gas to flow readily into wellbores. The term is used to make a distinction from shale and 

other unconventional reservoirs, in which gas might be distributed throughout the reservoir at the 

basin scale, and in which buoyant forces or the influence of a water column on the location of 

hydrocarbons within the reservoir are not significant. (5) 

Discharge: Any emission (other than natural seepage), intentional or unintentional. Includes, but is 

not limited to, spilling, leaking, pumping, pouring, emitting, emptying or dumping. (2) 

Disinfection byproduct (DBP): A compound formed by the reaction of a disinfectant such as 

chlorine with organic material in the water supply. (2) 

Drinking water resource: Any body of water, ground or surface, that could currently, or in the 

future, serve as a source of drinking water for public or private water supplies. 

DSSTox: The Distributed Structure-Searchable Toxicity Database Network, a project of the EPA's 

National Center for Computational Toxicology. The DSSTox website provides a public forum for 

publishing downloadable, structure-searchable, standardized chemical structure files associated 

with chemical inventories or toxicity datasets of environmental relevance. (2) 

Effluent: Waste material being discharged into the environment, either treated or untreated. (2) 

Environmental justice: The fair treatment of people of all races, cultures, incomes, and 

educational levels with respect to the development and enforcement of environmental laws, 

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regulations, and policies. The fair distribution of environmental risks across socioeconomic and 

racial groups. (2) 

Flowback: After the hydraulic fracturing procedure is completed and pressure is released, the 

direction of fluid flow reverses, and water and excess proppant flow up through the wellbore to the 

surface. The water that returns to the surface is commonly referred to as “flowback.” (3) 

Fluid formulation: The entire suite of products and carrier fluid injected into a well during 

hydraulic fracturing. 

Formation: A geological formation is a body of earth material with distinctive and characteristic 

properties and a degree of homogeneity in its physical properties. (2) 

Formation water: Water that occurs naturally within the pores of rock. (5) 

FracFocus: National registry for chemicals used in hydraulic fracturing, jointly developed by the 

Ground Water Protection Council and the Interstate Oil and Gas Compact Commission. Serves as an 

online repository where oil and gas well operators can upload information regarding the chemical 

compositions of hydraulic fracturing fluids used in specific oil and gas production wells. Also 

contains spatial information for well locations and information on well depth and water use. 

Geographic information system (GIS): A computer system designed for storing, manipulating, 

analyzing, and displaying data in a geographic context, usually as maps. (2) 

Gross α: The total radioactivity due to alpha particle emission as inferred from measurements on a 

dry sample. (2) 

Gross β: The total radioactivity due to beta particle emission as inferred from measurements on a 

dry sample. (2) 

Ground water: The supply of fresh water found beneath the Earth’s surface, usually in aquifers, 

which supply wells and springs. It provides a major source of drinking water. (2) 

Halite: A soft, soluble evaporate mineral commonly known as salt or rock salt. Can be critical in 

forming hydrocarbon traps and seals because it tends to flow rather than fracture during 

deformation, thus preventing hydrocarbons from leaking out of a trap even during and after some 

types of deformation. (5) 

Hazardous air pollutants: Air pollutants that are not covered by ambient air quality standards but 

which, as defined in the Clean Air Act, may present a threat of adverse human health effects or 

adverse environmental effects. Although classified as air pollutants, they may also impact drinking 

water. (2) 

Horizontal drilling: Drilling a portion of a well horizontally to expose more of the formation 

surface area to the wellbore. (1) 

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Hydraulic fracturing: The process of using high pressure to pump sand along with water and 

other fluids into subsurface rock formations in order to improve flow of oil and gas into a wellbore. 

(1) 

Fluid: Specially engineered fluids containing chemical additives and proppant that are 

pumped under high pressure into the well to create and hold open fractures in the 

formation. 

Wastewater: Flowback and produced water, where flowback is the fluid returned to the 

surface after hydraulic fracturing has occurred but before the well is placed into production, 

and produced water is the fluid returned to the surface after the well has been placed into 

production. 

Water cycle: The cycle of water in the hydraulic fracturing process, encompassing the 

acquisition of water, chemical mixing of the fracturing fluid, injection of the fluid into the 

formation, the production and management of flowback and produced water, and the 

ultimate treatment and disposal of hydraulic fracturing wastewaters. 

Hydraulic gradient: Slope of a water table or potentiometric surface. More specifically, change in 

the hydraulic head per unit of distance in the direction of the maximum rate of decrease. (2) 

Hydrocarbon: An organic compound containing only hydrogen and carbon, often occurring in 

petroleum, natural gas, and coal. (2) 

Immiscible: The chemical property where two or more liquids or phases do not readily dissolve in 

one another, such as soil and water. (2) 

Integrated Risk Information System (IRIS): An electronic database that contains the EPA's latest 

descriptive and quantitative regulatory information about chemical constituents. Files on chemicals 

maintained in IRIS contain information related to both noncarcinogenic and carcinogenic health 

effects. (2) 

Laboratory studies: Targeted research conducted to better understand the ultimate fate and 

transport of chemical contaminants of concern. The contaminants of concern may be components 

of hydraulic fracturing fluids, naturally occurring substances released from the subsurface during 

hydraulic fracturing, or treated flowback and produced water that has been released. 

Mass spectrometry: Method of chemical analysis in which the substance to be analyzed is heated 

and placed in a vacuum. The resulting vapor is exposed to a beam of electrons that causes 

ionization to occur, either of the molecules or their fragments. The ionized atoms are separated 

according to their mass and can be identified on that basis. (2) 

Material Safety Data Sheet (MSDS): Form that contains brief information regarding chemical and 

physical hazards, health effects, proper handling, storage, and personal protection appropriate for 

use of a particular chemical in an occupational environment. (2) 

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Monte Carlo simulation: A technique used to estimate the most probable outcomes from a model 

with uncertain input data and to estimate the validity of the simulated model. 

National Pollution Discharge Elimination System (NPDES): A national program under Section 

402 of the Clean Water Act for regulation of discharges of pollutants from point sources to waters of 

the United States. Discharges are illegal unless authorized by an NPDES permit. (2) 

National Response Center (NRC): Communications center that receives reports of discharges or 

releases of hazardous substances into the environment. Run by the US Coast Guard, which relays 

information about such releases to the appropriate federal agency. (2) 

Natural gas or gas: A naturally occurring mixture of hydrocarbon and non-hydrocarbon gases in 

porous formations beneath the Earth’s surface, often in association with petroleum. The principal 

constituent of natural gas is methane. (5) 

Natural organic matter (NOM): Complex organic compounds that are formed from decomposing 

plant animal and microbial material in soil and water. (2) 

Offset wells: An existing wellbore close to a proposed well that provides information for planning 

the proposed well. (5) 

Overburden: Material of any nature, consolidated or unconsolidated, that overlies a deposit of 

useful minerals or ores. (2) 

Peer review: A documented critical review of a specific major scientific and/or technical work 

product. Peer review is intended to uncover any technical problems or unresolved issues in a 

preliminary or draft work product through the use of independent experts. This information is then 

used to revise the draft so that the final work product will reflect sound technical information and 

analyses. The process of peer review enhances the scientific or technical work product so that the 

decision or position taken by the EPA, based on that product, has a sound and credible basis. 

Permeability: Ability of rock to transmit fluid through pore spaces. (1) 

Physicochemical properties: The inherent physical and chemical properties of a molecule such as 

boiling point, density, physical state, molecular weight, vapor pressure, etc. These properties define 

how a chemical interacts with its environment. 

Play: A set of oil or gas accumulations sharing similar geologic, geographic properties, such as 

source rock, hydrocarbon type, and migration pathways. (1) 

Porosity: Percentage of the rock volume that can be occupied by oil, gas or water. (1) 

Produced water: After the drilling and fracturing of the well are completed, water is produced 

along with the natural gas. Some of this water is returned fracturing fluid and some is natural 

formation water. These produced waters move back through the wellhead with the gas. (4) 

258



Proppant/propping agent: A granular substance (sand grains, aluminum pellets, or other 

material) that is carried in suspension by the fracturing fluid and that serves to keep the cracks 

open when fracturing fluid is withdrawn after a fracture treatment. 

Publicly owned treatment works (POTW): Any device or system used in the treatment (including 

recycling and reclamation) of municipal sewage or industrial wastes of a liquid nature that is 

owned by a state or municipality. This definition includes sewers, pipes, or other conveyances only 

if they convey wastewater to a POTW providing treatment. (2) 

Quality assurance (QA): An integrated system of management activities involving planning, 

implementation, documentation, assessment, reporting, and quality improvement to ensure that a 

process, item, or service is of the type and quality needed and expected by the customer. (2) 

Quality assurance project plan (QAPP): A formal document describing in comprehensive detail 

the necessary quality assurance procedures, quality control activities, and other technical activities 

that need to be implemented to ensure that the results of the work performed will satisfy the stated 

performance or acceptance criteria. (2) 

Quality Management Plan: A document that describes a quality system in terms of the 

organizational structure, policy and procedures, functional responsibilities of management and 

staff, lines of authority, and required interfaces for those planning, implementing, documenting, and 

assessing all activities conducted. (2) 

Radionuclide: Radioactive particle, man-made or natural, with a distinct atomic weight number. 

Emits radiation in the form of alpha or beta particles, or as gamma rays. Can have a long life as soil 

or water pollutant. Prolonged exposure to radionuclides increases the risk of cancer. (2) 

Residuals: The solids generated or retained during the treatment of wastewater. (2) 

Safe Drinking Water Act (SDWA): The act designed to protect the nation's drinking water supply 

by establishing national drinking water standards (maximum contaminant levels or specific 

treatment techniques) and by regulating underground injection control wells. (2) 

Scenario evaluation: Exploration of realistic, hypothetical scenarios related to hydraulic fracturing 

activities using computer models. Used to identify conditions under which hydraulic fracturing 

activities may adversely impact drinking water resources. 

Science Advisory Board: A federal advisory committee that provides a balanced, expert 

assessment of scientific matters relevant to the EPA. An important function of the Science Advisory 

Board is to review EPA’s technical programs and research plans. 

Service company: A company that assists well operators by providing specialty services, including 


Shale: A fine-grained sedimentary rock composed mostly of consolidated clay or mud. Shale is the 

most frequently occurring sedimentary rock. (5) 

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Solubility: The amount of mass of a compound that will dissolve in a unit volume of solution. (2) 

Sorption: The act of soaking up or attracting substances. (2) 

Source water: Water withdrawn from surface or ground water, or purchased from suppliers, for 


Spud (spud a well): To start the well drilling process by removing rock, dirt, and 

other sedimentary material with the drill bit. 

Standard operating procedure (SOP): A written document that details the method of an 

operation, analysis, or action whose techniques and procedures are thoroughly prescribed and 

which is accepted as the method for performing certain routine or repetitive tasks. (2) 

Statistical analysis: Analyzing collected data for the purposes of summarizing information to make 

it more usable and/or making generalizations about a population based on a sample drawn from 

that population. (2) 

Surface water: All water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds, 

streams, impoundments, seas, estuaries, etc.). (2) 

Surfactant: Used during the hydraulic fracturing process to decrease liquid surface tension and 

improve fluid passage through the pipes. 

Technical systems audit (TSA): A thorough, systematic, onsite, qualitative audit of facilities, 

equipment, personnel, training, procedures, record keeping, data validation, data management, and 

reporting aspects of a system. (2) 

Tight sands: A geological formation consisting of a matrix of typically impermeable, non-porous 

tight sands. 

Total dissolved solids (TDS): The quantity of dissolved material in a given volume of water. (2) 

Toxicity reference value: A reference point (generally a dose or concentration) where exposures 

below that point are not likely to result in an adverse event/effect given a specific range of time. 

Toxic Substances Control Act (TSCA): The act that controls the manufacture and sale of certain 

chemical substances. (2) 

Unconventional resource: An umbrella term for oil and natural gas that is produced by means 

that do not meet the criteria for conventional production. What has qualified as unconventional at 

any particular time is a complex function of resource characteristics, the available exploration and 

production technologies, the economic environment, and the scale, frequency, and duration of 

production from the resource. Perceptions of these factors inevitably change over time and often 

differ among users of the term. At present, the term is used in reference to oil and gas resources 

whose porosity, permeability, fluid trapping mechanism, or other characteristics differ from 

conventional sandstone and carbonate reservoirs. Coalbed methane, gas hydrates, shale gas, 

fractured reservoirs, and tight gas sands are considered unconventional resources. (5) 

260



Underground Injection Control (UIC): The program under the Safe Drinking Water Act that 

regulates the use of wells to pump fluids into the ground. (2) 

Underground injection control well: Units into which hazardous waste is permanently disposed 

of by injection 0.25 miles below an aquifer with an underground source of drinking water (as 

defined under the SDWA). (2) 

Underground source of drinking water: An aquifer currently being used as a source of drinking 

water or containing a sufficient quantity of ground water to supply a public water system. USDWs 

have a total dissolved solids content of 10,000 milligrams per liter or less and are not aquifers 

exempted from protection under the Safe Drinking Water Act. (40 CFR 144.3) (2) 

Vapor pressure: The force per unit area exerted by a vapor in an equilibrium state with its pure 

solid, liquid, or solution at a given temperature. Vapor pressure is a measure of a substance's 

propensity to evaporate. Vapor pressure increases exponentially with an increase in temperature. 

(2) 

Viscosity: A measure of the internal friction of a fluid that provides resistance to shear within the 

fluid. (2) 

Volatile: Readily vaporizable at a relatively low temperature. (2) 

Wastewater treatment: Chemical, biological, and mechanical procedures applied to an industrial 

or municipal discharge or to any other sources of contaminated water in order to remove, reduce, 

or neutralize contaminants. (2) 

Water withdrawal: The process of taking water from a source and conveying it to a place for a 

particular type of use. (2) 

Well files: Files that generally contain information regarding all activities conducted at an oil and 

gas production well. These files are created by oil and gas operators. 

Well operator: A company that ultimately controls and operates oil and gas wells. 

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References 

1. Oil and Gas Mineral Services. 2010. Oil and Gas Terminology. Available at 

http://www.mineralweb.com/library/oil-and-gas-terms/. Accessed January 20, 2011. 

2. US Environmental Protection Agency. 2006. Terminology Services: Terms and Acronyms. 

Available at http://iaspub.epa.gov/sor_internet/registry/termreg/home/overview/ 

home.do. Accessed January 20, 2011. 

3. New York State Department of Environmental Conservation. 2011. Supplemental Generic 


(revised draft). Well Permit Issuance for Horizontal Drilling and High-Volume Hydraulic 


Available at ftp://ftp.dec.state.ny.us/dmn/download/OGdSGEISFull.pdf. Accessed January 

20, 2011. 

4. Ground Water Protection Council and ALL Consulting. 2009. Modern Shale Gas 

Development in the US: A Primer. Ground Water Protection Council and ALL Consulting for 

US Department of Energy. Available at http://www.netl.doe.gov/technologies/oilgas/publications/epreports/shale_gas_primer_2009.pdf. 


5. Schlumberger. Oilfield Glossary. Available at http://www.glossary.oilfield.slb.com/. 


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